A Systematic Treatment of Fruit Types
World Botanical Associates Web Page
Prepared by Richard W. Spjut
Apr 2003, Mar 2004; Feb. 2006; Mar 2007; Sep 2007, Jan 2008, Mar 2009, Jan 2011, Feb 2012. Jan 2015
Note: Translated into Estonian by Anna Galovich, 6 Sep 2011, web site no longer available
What is a fruit?
Classification of Fruit Types
How Fruits are Classified
Pericarpium and Anthocarp: Their Classification According to Gynoecial Structures
Basic Types of Pericarpia According to Gynoecial Structures
Basic Types of Anthocarps According to Gynoecial Structures
Overview of Fruit Concepts and Its Types
The Need For Standardized Meanings to Fruit Terms
What is a Nut? Another Example of a Term with Various Meanings in Carpology
The Pistillate Concept of Fruit
Further Considerations to Recognizing Fruit Types
Proposed Rules of Carpological Nomenclature
Notes and Corrections
Reviews and Useful Publications on Fruits:
Fruits and Seeds of Dicots of Brazil (Barroso et al. 1999)
Fruits of the Australian Tropical Rainforest (W. Cooper & W. T. Cooper 2004)
Tropical and Subtropical Trees. An Encyclopedia (Margaret Barswick 2004)
Seeds. The Time Capsules of Life (Rob Kesseler & Wolfgang Stuppy 2006)
Fruit: Edible, Inedible, Incredible (Wolfgang Stuppy & Rob Kesseler 2008)
Selected References (old photocopies in pdf format of historical references)
Acknowledgments to Contributors of Websites
The concept "fruit" and the terminology descriptive of fruit morphology are defined to distinguish the different kinds (types). Some of the advantages and disadvantages to previous classifications of fruit types are discussed; the criteria considered to be the most useful are adopted for a new systematic treatment. This new treatment includes: (1) a key to 95 fruit types, (2) a systematic review of their names and definitions, and (3) an index to carpological terms. In the key up to six examples for each kind of fruit are indicated by reference to family (genus) name. In the systematic review each fruit is defined; this is followed by (1) references to the original author and others who have applied the accepted term and/or its synonyms; (2) a discussion of its relationships to other kinds of fruits, and (3) citations of specimens, illustrations, and/or descriptions of taxa studied. Thirty-seven new names or nomenclatural modifications to previous names for fruit types are made. The materials studied are referenced by species names under family names according to the classification of Cronquist (1981) for angiosperms (Magnoliophyta), and accepted family names by Airy Shaw (1973) for gymnosperms. Names for all fruit types are also listed in the index with reference to the original author, the date and place of publication, and the definition as originally presented by the author for each term; additionally, the index includes other carpological terms and their definitions.
Spjut, R. W. and J. Thieret. 1989. Confusion between multiple and aggregate fruits. The Botanical Review 55: 53–72. http://www.carnegiemuseums.org/cmag/bk_issue/1997/julaug/dept1.htm
Stuppy, W. and R. W. Spjut. In Prep. Dictionary of Fruit and Seed Biological Terms. Includes not only technical terms but also common names of plants with reference to fruit names. Expect 200–250 pages with many illustrations and photographs.
What is a fruit?
A fruit is a propagative unit developing from one or more fertilized egg cells (or rarely by parthenocarpy) enclosed by integuments and attached to megasporophylls, or a megasporophyll-scale complex, in a strobilus, cone, gynoecium, concrescent gynoecia, or gynoecia that disseminate together at the time it or its seed(s) are dispersed from the plant, or just prior to germination on the plant, and it may also include any other attached scales, bracts, modified branches, perianth, or inflorescence parts.
Note: Text highlighted
are links to photos at other websites, which are
A. Spermatocarpia (“naked seeds”)
Spermidium. Seed lacking bracts or
scales, integuments drupaceous, the outer fleshy, inner
B. Eucarpia (“covered seeds”)
I. Simple Fruits. Seeds not dispersed from pericarpium, developing from one flower.
Angiocarpi. Accessory (floral) parts enlarging with maturation
Tryma. Anthocarp dehiscent (Arecaceae [Astrocaryum munbaca],
Glans. Pericarpium subtended (basally) by accrescent floral
parts (receptacle, peduncle,
Pseudoanthecium. Anthocarp of the Cyperaceae, the pericarpium in a
Seeds embedded in fleshy pulp without distinct endocarp Basellaceae
Gymnocarpi. Pericarpium developing without accessory floral parts, from one flower.
Lomentaceous Fruits. Pericarpium transversely
constricted into seed bearing segments,
Lomentum. Pericarpium of one carpel with complete disarticulation
Drupaceous Fruits. Pericarpium internally
differentiated by an endocarp, which may be of one or
Drupe. Pericarpium mostly fleshy except for endocarp (76+
families: Anacardiaceae [Mangifera36a
Simple Dry Fruits. Pericarpium not differentiated by endocarp, dry.
Samara. Pericarp extended into a wing, longer than the seed
(14+ families: Caesalpiniaceae
Simple Fleshy Fruits. Pericarpium not differentiated by endocarp, fleshy.
Bacca. Pericarpium with a thin outer skin-like layer, collapsing when removed
II. Rhexocarpic Fruits. Seeds dispersed by opening of pericarp.
Follicular Fruits (Of one Carpel)
Follicle. Opening along one suture, dorsal or ventral (Cercidiphyllaceae,
Capsular Fruits (Of more than one carpel)
Regular Capsules: Valves separating along sutures.
Complete Dehiscence: Opening 20% or more along sutures, without columella.
Septicidal Capsule. Opening along ventral suture (35+
families: Dilleniaceae (Dillenia
Incomplete Dehiscence: Opening <20% along sutures, or with
persistent replum or columella, or
Denticidal Capsule. Opening only part way, < 20%
of suture length
Irregular Capsules: Localized sutures or pores, or breaking apart along
cracks, or rupturing from
Pyxidium. Capsule opening by a lid, or a common pore, that encircles all carpels
III. Schizocarpic Fruits. Fruitlets derived from a compound pistil separating into its carpellary
With accessory parts
Glandarium. Receptacle accrescent (Ochnaceae [Ochna,88
Without accessory parts
Coccarium. Monocarps (fruitlets) opening along two sutures
(23+ families: Euphorbiaceae,89c
Baccarium. Endocarp indistinct (Apocynaceae [Hunteria],
IV. Multiple Fruits. A single flower producing multiple fruitlets (apocarps).
Discocarpi. Hypanthium, receptacle, or perianth enlarged or splitting in fruit.
Trymetum. Fruitlets dispersed by splitting of hypanthium (Monimiaceae105)
Etairionari. Multiple fruitlets without accessory (floral) parts.
Follicetum. Carpels (apocarps) opening along one suture (21+
Samaretum. Apocarps winged (Eupeteleaceae, Magnoliaceae [Liriodendron116]).
Drupetum. Seeds enclosed by a firm endocarp (Amborellaceae,
V. Compound Fruits. Derived from more than one flower.
Cryptocarpi. Fruitlets hidden by floral parts.
Syconium. Fruitlets enclosed in a receptacle or peduncle (Moraceae
Phenocarpi. Fruitlets mostly exposed, which may include an accrescent perianth.
Folliconum. Fruitlet of one carpel (Proteaceae [Banksia130]).
Glandosum. Fruitlets on a swollen base (peduncle or receptacle, Urticaceae [Procris].
Anthecocarpi. Fruitlets in a spikelet of one or more florets, mostly Poaceae.
Anthecium. Fruit derived from a spikelet with only one
floret, disarticulation always above glumes
Polyanthecetum. Inflorescence breaking up along the rachis at
pedicillate nodes (Lycurus,
different kinds of fruit types may seem overwhelming, most names for fruit
types belong to 14 terms that have a common stem, nine types of
simple pericarpia (camara, follicle, coccum, achene, bacca, drupe,
capsule, samara, loment) and five types of simple anthocarps (anthecium,
dicelsium, pome, tryma, glans). The names for
fruit types then differ only by a common suffix, or are distinguished by a descriptive
adjective according to
different categories of fruit types that are recognized.
The different categories are based on three types of gynoecial structures
flower, and the distinction between fruits derived from one flower
and more than one flower. The gynoecial types are:
(1) Apocarpous—of one carpel, or of many distinct carpels that
remain distinct or become fused
Additionally, compound (aggregate) gynoecia are recognized when they become united to form a compound fruit (of more than one flower).
The concept of fruit itself has been confused along with another term anthocarp. For consistent application of fruit terminology, it was necessary to define anthocarp, and to distinguish it from what is often defined as fruit in the literature, the pericarpium.
What is a pericarpium? A ripened ovary without any attached floral parts. A fruit may consist of nothing more than a pericarpium.
There are ten common (simple) types of pericarpia:
Camara—dry and indehiscent or
irregulary dehiscent, unicarpellate, the pericarp free from the testa.
As shown below, the name endings for eight of the above names for pericarpia are modified according to gynoecial type: etum for fruit types that fall under the category of multiple fruits, arium for fruit types that fall under the category of schizcarpic fruits, and osus, osum or conum for fruit types that fall under the category of compound fruits.
The common Latin endings and their meanings are as follows, from Stearn's Botanical Latin (1983): “arium" —“indicates a place where something is done or a container, “or in this classification the breaking apart of a container (schizocarpic fruits, grass spikelets); “etum"— “indicates collective place of growth" such as the mature gynoecium in multiple fruits; and “osus -a -um"—“indicates abundance or full or marked development," as seen in the concrescent gynoecia of compound fruits. In compound fruits that resemble a cone, the term "conum" is appended instead of the suffix “osum" (e.g., achenoconum, folliconum). As a result of creating compound terms, or appending suffices to terms, a more abbreviated concatenation is occasionally used for a more pleasing sound (e.g., samarium instead of samararium).
Fruit types with less familiar names include the schizocarpic fruits—microbasarium (mostly Lamialeas) and the polachenarium (mostly Apiaceae). Here it might be noted that fruitlets of the microbasarium in the Lamiales (sensu Cronquist 1981)—commonly referred to as a fruit of four "nutlets" are really four mericarps. Mericarp is a more appropriate term for a fruitlet of the Lamiales, and other families, in which a bilobed carpel divides into two halves as it matures. The term microbasarium was adopted from microbase of de Candolle in his “Théorie Élémentaire del la Botanique” (in 1813) where he noted that the fruitlets of the microbasarium were not naked seeds as previously thought. Alternatively, bilomentarium might be a better term, which although has not been employed by anyone, it was decided that the established name, microbasis, should be adopted to avoid confusion with bilomentum as defined by Beck in 1891 for a two carpellate fruit that breaks apart transversely into seed bearing segments as in Raphanus, in contrast to the unicarpellate lomentum of the Fabales.
Capsule is common type of pericarpium that is a product of a fruiting syncarpous gynoecium. Seven different kinds of capsules are distinguished by adjectives, instead of by different endings, while another, capsiconum, is a product of aggregate gynoecia. Two others without the term capsule had names already well-established in the literature; these are siliqua and pyxidium. One common type of capsule with a less familiar name is the ceratium, a term employed by Lindley that surprisingly has been neglected in view of the fact that much of his terminology has been adopted.
Names for two other types were created, polospermatium and glandispermidium; these are didactically related to polachenarium, glans, and spermidium.
In other cases, however, the stem in terms under compound fruits were lumped under one name ending to avoid creating more names, e.g., the fruitlets consisting of one carpel that opens along one suture (follicle of an apocarpous gynoecium) and those that open along two sutures (coccum of an apocarpous gonecium) are all considered a folliconum in a compound fruit.
Six basic types of anthocarps are recognized:
Glans—receptacle or pedicel or
The first four terms are employed in the different classes of gynoecial structures; these are exemplified as follows:
It should be noted that there are some exceptions to name endings and their classification. For instance, the suffix “arium" which is commonly used to designate a schizocarpic fruit, includes pomarium, a multiple fruit; the suffix (arium) refers to the division of the receptacle into many cavities. Anthecetum and anthecarium are compound fruits; the former is a collection of florets and glumes, in addition to the fertile floret that contains the pericarpium, and the latter name reflects the breaking apart (disarticulation) of a rachilla from which several or more fertile florets are individually dispersed. Other exceptions are with fruit names that have been well-established in the literature; it was decided that these names should be retained, e.g., the compound fruit—syconium—for the fruit of the fig (Ficus).
Overview of Fruit Concepts and The Different Kinds (Types)
There has been considerable disagreement during the past several centuries on the scientific terms employed to distinguish the different kinds of fruits and their definitions—such as achene, nut, and others (Gray 1880; Levina 1961; Lindley 1832; Schleiden 1849; Spjut & Thieret 1989; Spjut 1994).
The lack of agreement on the distinction of fruit types, their names (or terms) and their definitions are all tied to the controversial concept of fruit itself. Beginning with the first textbook of botany, Linnaeus' Philosophia botanica of 1751 (Rickett 1944; Stearn 1983), the concept of fruit may include just the seed as well as the parts that cover the seed(s) that form a dispersal unit (naked seeds vs. covered seeds). Linnaeus' covered seeds included the pericarpium (mature ovary, Lindley 1831) for which he recognized seven different types referred to as capsula, siliqua, legumen, conceptaculum (= follicle), drupa, pomum, bacca, and "strobile." The latter included seed-scale complexes in gymnosperms. The pericarpium and its types were one of seven categories of "Fructificatio" that included the calyx, corolla, stamen, pistillum. pericarpium, semen and receptaculum. Essentially, fructification of Linnaeus (1751) was the flower and the fruit (Barton 1827; Rickett 1954). In present day botany, determining a fruit type requires tracing its ontogeny from the flower stage.
A major comprehensive taxonomic treatment of fruits and seeds was that of Gaertner (1788–92). He applied the fruit concept of naked vs. covered seeds, frequently employing the term pericarpium (a seed conceptacle derived from an ovary) without mentioning the term fruit in describing fruits and seeds of genera and species, except when the pericarp ("pericarpio," fruit wall) was indicated to be absent, or occasionally both fruit ("fructus") and pericarpium were mentioned in descriptions of gymnosperm fruits (cones). For example, the cone of Juniperus was referred to as a fruit ("fructus") by the name of galbulus (= arcesthida of Desvaux 1813; Spjut 1994) that contained a nut type of pericarpium (fleshy scales that unite at maturity and completely enclose bony seeds); similarly, the cone of Thuja contained a nut (pericarpium) in a strobilus ("fructus") (Gaertner 1791).
One problem Linnaeus' and Gaertner's "naked seeds" is that they were not always "naked" (L-C Richard 1808 [Lindley 1819], 1811; Brown 1818), except gymnosperms (Brown 1827). Botanists had come to realize that not only all flowering plants (angiosperms) produce seeds that develop within an ovary of a flower, but that all gymnosperms produce seeds attached to ovuliferous scales in which there are no pericarpia (mature ovaries), a sharp distinction between gymnosperms ("naked seeds") and angiosperms ("covered seeds") (Lindley 1830, 1831). Nevertheless, the concept of fruit still applied to both angiosperms and gymnosperms; for example, Lindley (1832) had stated that "every fruit consists of two principal parts, the pericarpium and the seed" with exceptions he noted earlier under his principles of fruit and seed that "Cycadeae and Coniferae...have no ovarium" (Lindley 1830, 1831, #423), and that "all seeds are matured ovula...originally enclosed within an ovarium," and that "naked seeds cannot exist"; "Cycadeae and Coniferae are the only exceptions to this" (Lindley 1830, 1831, #471-72). Thus, gymnosperm were still recognized to bear fruit even though their seeds did not develop in an ovary. These principles were generally followed not only through the 19th century (e.g., Gray 1880, 1887; von Marilaun 1895) but well into the 20th century (e.g., von Beck 1913, Hertel 1959; Sampaio 1943). The concept of fruit being more associated with the angiosperm pericarpium than with the gymnosperm seed-scale complex seems to have been advanced primarily during the 20th century following discovery of double fertilisation by Navashin (1898) and arguments made by others that fruit (based on the pericarpium alone) should not be equated with seed cone structures of gymnosperms because they are not homologous (Gibson 1909).
However, the angiosperm concept of fruit has remained controversial in other respects that relate to the development of a complex seed dispersal unit (diaspore or fruit). Fruit may be interpreted as just part of a complex dispersal structure such as a half-carpel (mericarp) of borages, or just one of many separate fruiting carpels that develop from a single flower (fruitlet, pistillate concept of fruit) as in the buttercup (Ranunculus), or it may include all the mature carpels of a buttercup (multiple fruit, gynoecial concept of fruit), or in the strawberry, Fragaria x ananassa (Weston) Duchesne ex Rozier, it may include the extra-gynoecial (accessory) parts such as the accrescent receptacle (multiple anthocarp, Discocarpi of Spjut 1994, specifically a glandetum), or it may be an entire aggregate of pericarpia derived from an inflorescence as in the mulberry (compound fruit, specifically a sorosus in Morus). Fruit in the latter two cases also falls under a concept of "false-fruit," one composed of extra ovarian parts that still includes the "true fruits," a practice regarded by Spjut (1994) as a double standard.
Where does one draw the line? Should fruit be the smallest carpellary unit, or should it be the entire seed-megasporophyll complex and whatever disperses with it, or should exceptions be allowed in which more than one standard can be applied to define the various fruit types as whatever the case may be as indicated by Gray (1880)? The significance of the ovary in angiosperms is the added protection to the event of fertilization and development of the seed. However, floral (accessory) structures that often develop in fruit generally play a greater role than the pericarp in the seed dispersal, while it may also be noted that scales of conifer cones usually close around the ovule after fertilization. As the pericarp becomes less significant in seed dispersal, so too does the concept of fruit being tied to the pericarp. Gymnosperms also exhibit various seed dispersal strategies involving accessory structures such a closed and open cones in Pinus, which mature closed cones require fire or birds for opening, fleshy cones (e.g., Juniperus), cones that break apart at maturity (e.g., Abies, Larix, Taxodium), arillate seeds (e.g., Taxus), and accrescent colourful scales (e.g., Podocarpus).
Fruit types are often recognized by monomials or binomials in context much like common and scientific names given to plant genera and species, and fruit nomenclature sometimes has been justified in a manner that is similar to the International Code of Botanical Nomenclature (ICBN). An example is hesperidium, a technical name for a fruit represented by the orange (Citrus sinensis [L.] Osbeck), created by Desvaux (1813) as a substitute name for the term "L'Orange" of de Candolle (1813); i.e. de Candolle's (1813) technical name was the same as the colloquial name ("L'Orange"). Desvaux had agreed with de Candolle that the orange fruit was distinct from other fruit types, but felt that his substituted name was a better choice because de Candolle's name in usage appeared contradictory; for instance, the lime (Citrus aurantiifolia [Christm.] Swingle), which was considered the same kind of fruit, would also be called an orange. The name hesperidium is from a Greek mythological figure (nymph) associated with a garden in Hesperides, a place where golden apples (oranges evidently) were grown. Thus, the term hesperidium has nothing to do with the morphological attributes that defined the fruit (hesperidium), which is known for its juicy swollen hairs. Nonetheless, Desvaux's (1813) reasoning for providing a substitute name seems appropriate, while it may be noted other names have been proposed; Pool (1929), for example, suggested citrocarp would be a better name "since hesperidium has a purely fanciful mythological origin." Ironically, hesperidium was the only one of 20 novelty names by Desvaux (1813) that has been generally accepted in modern botanical textbooks (Spjut 1994 accepted additional terms), while not always applied in technical botanical descriptions of citrus plants.
A major conflict in the application of fruit terminology as it relates to the concept of fruit is perhaps best understood by example such as the apple (Malus × domestica Borkh.). Botanists who adhere strictly to defining fruit by the pericarp layer might view the fruit of Malus × domestica as a "membranous capsule" (Barton 1827), or as a carcerulus enclosed by a fleshy or fruiting hypanthium in which the fruit essentially lies hidden at the core. In practice, however, no one seems to apply such a strict definition to a Malus fruit. As indicated by Pool (1929), "the 'core'" is "not included in the popular conception of a fruit" because it is "not eaten, unless perchance one is very hungry." While one's familiarity with the apple helps in this example, there are many other less familiar examples where it is difficult to a decide just where the pericarp ends and the external fruiting perianth cover begins, especially in fruits derived from an inferior ovary. Botanists have tried to resolve this problem in several ways; by giving different names to fruit types derived from an inferior ovary in contrast to those derived from a superior ovary (e.g., Desvaux 1813; Lindley 1832), or by simply referring to all inferior fruits as false fruits (Johnson 1931) or accessory fruits (Schmid 1982), the so-called double standard (Spjut 1994).
Whether one employs a narrow or broad concept of fruit, or one in between, many of the same terms are still adopted. For example, the term achene has been applied as a name for (1) a fruit of an individual mature carpel of a buttercup derived from a superior ovary, or (2) all of the achenes may be recognized as fruit while an individual achene is also called a fruit, a double standard, (3) or an individual mature bicarpellate fruit of the sunflower, which is derived from an inferior ovary, or (4) a mature ovary of a strawberry in which the fleshy part is not considered part of the fruit but may be called a false fruit (double standard), or (5) a mature ovary of a mulberry, derived from a single flower of an aggregate (compound fruit). Such a variable concept of fruit and fruit type has led to various definitions for the term achene, and to the creation of new terms to help narrow the definition of achene.
Spjut (1994) found that the most logical solution was to adopt a broad concept of fruit. It was only in this manner that a functional classification of fruit types and their names could be produced that would be consistent with the overall definition of fruit, and would also allow one to adopt many older fruit terms that appeared useful (Gray 1880); Spjut (1994) adopted many of the already established carpological terms instead of creating new terms. Nonetheless, a major drawback with the application of previous carpological terms has been the lack of relationships among the terms themselves (Lindley 1832). Names such as microbassis (de Candolle 1813), xylodium and acrosarcum (Desvaux,1813), may, on one hand, relate to a character feature of the fruit, but on the other hand, not to each other, or to other botanical terms.
Hierarchical classifications such as Mirbel (1813, 1815) who grouped terms into "orders," "genera", and "forms" still lacked lack mnemonic attributes among the terms. Mirbel (1813, 1815) names for fruit "forms" were much like species binomials in distinguishing the different forms within a genus of fruits; for example, the hedge mustard (Sisymbrium officinale [L.] Scop.) was referred to as a Siliqua cylindrica. in contrast to that of the cultivated radish (Raphanus sativus L.), a Siliqua turgida, both classified in the order Capsulaires (Mirbel 1815). This type of nomenclature might be confused with Latin names given to the species and higher taxa to which the fruit belongs. Kaden and Kirpieznikov (1965) suggested a similar type of nomenclature system by adopting the generic names of plants as standards for fruit types within each family (e.g., brassicocarpium for Brassica and related genera), This was a much narrower fruit concept but otherwise similar to general fruit terms that have been recognized as applicable only to a certain family of plants as exemplified by the caryopsis, siliqua, and legume (Cronquist 1961).
Generally, fruits have been defined and classified in several ways.
Mnemonic names, monomial or binomial, that
are appropriate in meaning to a fruit type but can be created to reflect.
(2) a systematic method of describing fruits based on standardized set of terms used to designate fruit characters and their character states (e.g., Baumann-Bodenheim 1954).
The Need for Standardized Meanings to Fruit Terms:
As indicated above, the first text book of botany might be regarded as Carl Linnaeus' Philosophia Botanica (1751). Linnaeus (1751, 1759) recognized only eight different kinds of fruits (capsula, siliqua, legumen, folliculus, drupa, pomum. bacca and strobilis; his binomial system of nomenclature in describing plants and animals (e.g., Species Plantarum in 1753) has since been established as a starting point for the International Code of Botanical Nomenclature (ICBN). Subsequently, Joseph Gaertner, in a four-volume De Fructibus et Seminibus Plantarum (1788–1792), described and illustrated in considerable detail fruits and seeds of more than 1,000 species. Gaertner’s (1788-1792) terms for distinguishing fruits included eight terms established by Linnaeus (1751,1759), and seven others—samara, acinus, nux, coccum, galbulus, pepo, and utriculus.
The terms that appeared in both Linnaeus (1751) and Gaertner (1788-1792) are widely accepted today, but two of Gaertner’s terms—nux (nut) and utriculus (utricle)—have acquired various meanings in which there is no agreement as to how they should be defined (Lindley 1832, Spjut 1994). For example, Gaertner (1788) had defined nut as a pericarp with a hard texture in contrast to a berry that is soft and fleshy, whereas L-C. Richard (1798, 1808) regarded nut as what is commonly regarded today as a stone within a drupe or nuculanium. Judd et al. (2002) define nut sensu Gaertner (1788), based on the pericarpium alone; i.e., the accessory structures are ignored in their examples given for fruits (nuts) of Castanea, Corylus, Dipterocarpus, Fagus, and Quercus, whereas in the case of a drupe, the accessory structures are included as they exemplify by citing Juglans.
It might be noted that among the terms for fruit types in Linnaeus (1751, 1759) and Gaertner (1788-1792) with less controversial meanings, only five have had broad taxonomic application—drupa, bacca, samara, capsula and folliculus, while five others have had limited taxonomic scope—siliqua (Brassicaceae), legume (Fabaceae), pepo (Cucurbitaceae), pome (Maloideae), galbulus (Cupressaceae) and strobilus (conifers). Are these ten terms adequate for classifying all the different kinds of fruits?
Botanists since Gaertner (1788-1792) have generally focused on establishing classification terms and standards for naming fruit types; yet, relatively few fruit terms have become established from other sources. Achene from Necker (1790) and caryopsis from L.C. Richard (1811) are examples of two terms for fruit types that are commonly accepted by modern taxonomists; the former is recognized to occur in many plant families, while the latter is another example of a term with limited taxonomic application—pericarpium of the Poaceae.
Additionally, L-C. Richard (1798, 1808) established that the pericarp can be divided into three layers (epicarp, sarcocarp, endocarp), and that the inner layer of the pericarp can become differentiated into one or more stones (nuculae). He also defined dehiscence types for capsular fruits such as loculicidal, septicidal, septifragal, and circumscissile, and provided illustrations for 15 fruit types, most of which were not described or defined; represented were caryopsis, achene, polachenium, glans, elaterium, follicula, silique (including silicule), gousse (= legume), capsule, drupe, nuculanium, melonidium, peponidium, berry and syncarpium (L-C. Richard 1798).
The need for more terms to comprehend the relationships among the wide diversity of fruit types became evident to three French botanists: Augustin de Candolle, Nicaise Auguste Desvaux, and Charles François Brisseau de Mirbel. In 1813, they independently published different fruit classifications, but Desvaux and Mirbel may have collaborated, while Desvaux (1813) had also made reference to de Candolle (1813). Among the three publications are 61 newly defined terms for fruit types, whereas the number of fruit types was considerably fewer in any one treatment, 28 in de Candolle, 29 in Mirbel, and 45 in Desvaux. Later, Brisseau de Mirbel (1815) decided there should be only 21 fruit types, instead of 29, whereas de Candolle (1819) proposed six more to his earlier 28, for a total of 34 fruit types. De Candolle (1819), in revising his classification of fruit types, accepted eight terms from Desvaux (1813) and Mirbel 1813, 1815)—hesperidium, xylodium, diersilis, regmatus, balausta, hemigyrus, dipotegium, and camara—as opposed to creating new terms.
Botanists today are uncertain as to which fruit types and terms should be recognized, perhaps because there are no rules to follow as in the case of the International Code of Botanical Nomenclature (ICBN) for naming plant species and their higher taxonomic levels (genera, families, orders, etc.), although similar rules were applied by Desvaux (1813). Nevertheless, the French botanists shared one important concept—that the fruit should include more than just the pericarpium—for which all three employed terms to describe fruits originating from one or more flowers, and they also recognized gymnosperm seed cones as fruit types (as also Linnaeus 1751). Such terms as sorosus and syconium — generally accepted in modern botanical text books — originate from Mirbel (1813). Another term commonly seen in modern textbooks, hesperidium, a simple fruit — similar to a berry — came from Desvaux (1813).
Nevertheless, attempts to bring order to carpological nomenclature continued. During the first half of the 19th century, comprehensive reviews were presented by A. Richard (1819, 1846), Gorianinow (1827, 1841), Lindley (1832, 1848), Bischoff (1833), and Dumortier (1835).
John Lindley, a well-known early 19th century English botanist—who translated Louis-Claude Richard's (1808) Analyse du Fruit into English and presented a revised classification of fruit types in his text book, Introduction to Botany (1832)—made the following comment on the French carpological classifications: “Each of the three writers (with reference to Desvaux, Mirbel, and A. Richard [Lindley was probably referring to de Candolle, not A. Richard] without dates of publication) has felt himself justified in contriving a nomenclature at variance with that of his predecessors, for reasons which it is difficult to comprehend,” and had also stated that “so much discordance, indeed, exists in the application of terms expressive of the modifications of fruit, that it is quite indispensable to give the definitions of some of the most eminent writers upon the subject in their own words, in order that the meaning attached by those authors to carpological terms, when employed by themselves, may be clearly understood.”
Unlike the French botanists, Lindley's fruit classification and general botanical glossary were accompanied by many illustrations. His works have been a major influence on modern botanical terminology. Yet, Lindley was not always consistent in his application of fruit terminology, and while he criticized others for being at variance, he himself inadvertently reversed the meaning of some terms that has led to confusion today between such terms as multiple fruits and aggregate fruits (Spjut & Thieret 1989).
As a result, the need for a clear understanding of the different fruit types and consistent application for their names became even more frustrating to others as expressed by Jacob Matthias Schleiden in his 2nd edition of "Principles of scientific botany" (English translation 1849 of German publication in 2 vols, 1845–1846). “Nowhere has purely diagrammatic comprehension been so prevalent as in the theory of the fruit', nowhere have botanists starting from the language of common life, and merely multiplying the words, taken so little pains to define with scientific strictness; and hence nowhere does terminology so vacillate among all the definitions as in the fruit. One assumes 10, another 14, a third 20, and another 40 or 60 kinds of fruit, in short, the confusion is indescribable.” “Here I will merely remark...that in the general treatment of the theory of the fruit they have been playing an unaccountably frivolous game with the reader or student. In any case, the manner in which the French in particular have increased nomenclature, is contrary to all laws of a sound terminology. Many as there are who praise or condemn Linnaeus, call him great or unintelligent, of all these not one has understood him, not one seen what he really attempted and how he attained it. It was a war against the nomenclature, heaping itself up with nothing but substantive words, which he began and happily carried though, by which means he, as with a magic touch, opened a thousand entrances into science previously impassable.”
Asa Gray was also major influence on establishing the meanings for botanical terms (Stearn 1983). His 1880 text book on structural botany (Gray 1880), unlike earlier editions, provided reasons as to why certain terms are preferred, particularly seen in his footnotes where he often added interesting comments such as recommending that collective fruit be substituted for aggregate fruit. Another reason why the use of additional fruit terms may be traced to Lindley (1832), is because Gray adopted Lindley’s classification of 36 fruit types in his (Gray 1836) first text-book of botany. Later, Gray (1880) recognized 22 kinds of fruits—(1) follicle, (2) legume, (3) loment, (4) capsule, (5) pyxis, (6) silique, (7) silicle, (8) schizocarp, (9) cremocarp, (10) mericarp (or hemicarp), (11) nutlets (or nucules), (12) samara, (13) caryopsis, (14) utricle, (15) nut, (16) glans, (17) drupe, (18) pome, (19) pepo, (20) hesperidium, (21) berry, and (22) achene (or achenium).
While de Candolle (1819), A. Richard (1819, 1846), Lindley (1832, 1848), Gray (1880), and others have worked towards reaching a consensus on the different kinds of fruits that should be recognized—including names and their definitions, there are those who continue to advocate new terms, and new meanings for old terms such as Beck (1913), Hertel (1959), and Barroso et al. (1999). Beck (1913) and Hertel (1959) applied new terms to distinguish angiosperm fruits from those of gymnosperms, while Hertel (1959) went much further in proposing that the concept of fruit (frutescence) be extended to seed ferns and lower vascular plants in which he distinguished fruit classes by names—Protalocarpo (“Selaginellales, Lepidophytales, Lepidospermae, Articulatae and Hydropteridales”), Archicarpo (“Pteriospermae, Cycadineae, Bennettitinae, Cordaitinae and Ginkyoinae”), Gymnocarpo (“Taxaceae”), Lepidocarpo (conifers excluding Araucariaceae), and Protocarpo (“Araucariaceae”). He also recognized simple, multiple and compound fruits sensu de Candolle (1813), but substituted his names—Eucarpo, Paracarpo, and Telocarpo, respectively. See table below.
Barroso et al. (1999) also adopted terms from Baumgratz (1985), Beck (1913), and Hertel (1959), and gave new meanings to old terms. A good example of a term that was given a new meaning is ceratium, first defined by Lindley (1832) as a fruit that is dehiscent by two valves, which separate from a replum, differing from the silqua in the lobes of the stigma being alternate with the placentae, not opposite, as exemplified in the Papaveraceae genera Corydalis, Glaucium and Hypecoum. This meaning was adopted by Spjut (1994) who broadened the definition to include, for example, the fruit of Proboscidea altheifolia (Benth.) Decne. Barroso et al.(1999), on the other hand, limited the definition of ceratium to just the fruit of Proboscidea altheifolia (Benth.) Decne. (Pedaliaceae), and in doing so they excluded the meaning as originally given by Lindley (1832). As noted in Spjut & Thieret (1989), “it has been suggested that in choosing among terms to attach to a definition, the term with the longer established meaning be given consideration rather than basing a decision on strictly priority (Aeschimann & Bocquet 1980; A. de Candolle 1880; Rickett 1944),” or etymology, or availability of literature. Furthermore, Spjut (1994) typified ceratium by the fruit of the species, Cleome viscosa L., in order to help conserve the meaning as originally defined by Lindley (1832). If we are going to advance the cause of nomenclatural stability, the meaning of ceratium as provided by Barroso et al. (1999) must be formally rejected.
Alternatives to classifying fruits by general terms include naming fruits by modifying generic names such as seen in Kaden and Kirpieznikov (1965 and other years), a “morpho-genetic” classification in which they distinguished fruit types by phylogenetic differences based on gynoecial morphology. Since plants traditionally are classified into families by floral morphology, and genera are often recognized within each family based on differences in fruit, they proposed names for each of the different fruit types within each family of plants. For example, in the Brassicaceae they recognized an “Alyssocarpium” based on the fruit characteristics of the genus Alyssum that would also include fruits in related genera such as Biscutella, Boleum, Carrichtera, Cardarai and Neslia, and a Brassicocarpium based on the fruit of Brassica that would include fruits in related genera such as Chorispora, Raphanistrum, and Raphanus. Obviously, these terms would be meaningful only to those who have knowledge of the floral and fruit morphological characteristics of the taxa mentioned. Consequently, one may recognize 1,000 or more fruit types based on ~15,000 genera of seed plants. Also, the non-generic (general) terms—caryopsis, legume, silique and silicle had already been recognized for pericarpia of the Poaceae, Fabaceae and Brassicaceae.
Others in Germany (Shultz-Shultzenstein 1864; Winkler 1939, 1940; Egler 1943; Baumann-Bodenheim 1954), in France (Germain de Saint Pierre 1869 and in Russia (Levina 1961), however, have suggested that fruits be described systematically according to standardized terms based on the morphology of the gynoecium and pericarpium. For instance, in Baumann-Bodenheim, the fruit of English Ivy, Hedera helix, could be described as a “Strato-Capsula gamo-marginalis, isocarpellata, interi-laminalis, margo = et apice-placentalis: ± isosperma. Pericarpium baccaceum, achlamydocarpum, asyncarpum” with “Clausicarpium” dehiscence (Kaden and Kirpieznikov 1965). In Spjut's Systematic Treatment of Fruit Types (1994), this is simply referred to as a pyxidium.
As stated by Levina On the Classification and Nomenclature of Fruits (Bot. J. 46: 488–495, 1961 in Russian), “there is a totally inadmissible muddle of terms and concepts, an obsolete anti-evolutionary classification of fruits which prevails in textbooks and sometimes even in specialized botanical literature. The necessity has arisen for establishment of a relative order in carpology and an agreement on some common, if not perfect, fruit nomenclature. It is important that botanists understand each other when they speak of achenes, nutlets and fruits.”
It would not serve any purpose here to review all carpological classifications. As indicated by Schleiden (1849), there are as many different classifications as there are botanical writers on the subject. The problem that continues to prevail is that reviews on fruit types are often published in botanical text-books without references, and those that are presented in journals with references lack a procedural basis for establishing their validity. In order to bring nomenclatural stability to fruit terms, the ICBN, or an internationally recognized committee of botanists, must establish a procedural basis for validation of a meaning associated with a particular botanical term.
The confusion over classification of fruit types and the definitions given to fruit terms can be seen today on the internet, while avoidance of using fruit names is also evident in well-used botanical manuals such The Jepson Manual Higher Plants of California (1993). Botanists for the past 200 years have been focused on identifying plants by floral characteristics, which are usually ephemeral; they have yet to systematically classify fruits, which usually persist on the plant long after maturity.
For didactic and mnemonic reasons, it would seem preferable to refer to fruits by terms that convey relationships to one another as opposed to deciphering lengthy technical descriptions or recalling fruit types by names based on that of a genus, or by simply inventing new names without regard to previous studies. An extreme example to illustrate this problem is the term bertolonidium (Baumgratz 1985), created in honor of a person, Antonio Bertoloni, a well-known Italian botanist, a term that was regarded as equivalent to a septifragal capsule (Spjut 1994). One cannot expect to associate the name of a person to a morphological structure. Even the use of generic names for fruit terms as proposed by Kaden and Kirpieznikov (1965) seems more desirable.
Although one learns to recall and relate organisms by their Latin (scientific) names, technical descriptions are nevertheless useful. Perhaps, names for fruit types and a systematic method for describing them in detail may eventually become standardized. Meanwhile, it seems that only more terms will continue to be created as evident in Barroso et al. (1999), reviewed in more detail below.
Nut has various meanings in the botanical literature that can be summarized as any hard dry fruit, or any part of a dry fruit characterized by a hardened tissue formed from exocarp (extra-ovarian parts), epicarp (outer pericarp layer), the entire pericarp, endocarp, and/or testa. These various meanings for nut, which were recognized long ago (L-C. Richard 1798), can be traced to the works of Pliny, Isidorus, Albertus Magnus and Ruellius’ Dioscorides (Sprague 1936).
In Albertus Magnus (1193–1280) De Vegetabilibus Libri VII “nuce” can refer to walnuts, coconuts, hazel-nuts, chestnuts, or acorns (Sprague 1933c). In the encyclopaediac works of Pliny the Elder, Historia naturalis (first printed 1469, followed by 190 editions until 1799, reportedly compiled from 473 authors of which 146 were Roman and 327 Greek; Stearn 1983), nut (nux) refers to fruits of Corylus, Castanea, Juglans, and Pistacia (Sprague 1933a). Related terms and their meanings in Pliny included balanus—acorn, nut of Quercus; putamen—shell of a walnut (Juglans), the stone (endocarp) of almond, the pericarp of a pod, or the rind (pericarp) of Punica; and glans—acorn, the nut of Quercus, or the nut of Fagus, or the nut-like seed of Moringa. In another encyclopaedist work, Isidorus Hispalensis (Sprague, Kew Bull; 1933b, A.D. 560-636), who apparently extracted much from Pliny (Stearn 1983), nux (nut) referred to “(1) the walnut tree:—“Hane alio nomine Latini iuglandem vocant, quasi Iovis glandem; (2) edible kernel with a hard rind; e.g., Pinus, Juglans, Corylus, Quercus, Castanea, Amygdalus communis:—Nuces autem generaliter dicuntur omnia poma corio duriori tecta, ut pineae, nuces, avellanae, glandes, castaneae, amygdalae. Hinc et nuclei dicti, quod sint duro corio tecti.” In Ruellius’ Dioscorides, from Sprague’s (1936) glossary, are:
Nucleus (1) the kernel of a nut, e.g. walnut, of Balanites aegyptiaca, a pine kernel (seed), (2) a stone (endocarp) of Crataegus pyracantha, Olea europaea; (3) the seed of Ruscus; Delphinium staphisagria; Vitis vinifera. (4): the hard seed of palms, Punica granatum.
Nux: (1) a nut, in contradistinction to nucleus, its kernel [seed], hence (2) the kernel of a nut or of a drupe, e.g., Corylus and Amygdalus communis.
Nux amara, a bitter almond, Amygdalus communis
Spjut and Thieret (1989) suggested that fruit terms and their meanings begin with Linnaeus (1751); however, Linnaeus (1751) defined nut as a type of seed: “semen tectum epidermide ossea” (a seed covered with a hard bony skin). This rather simple definition has since been complicated by the fact that the nuts Linnaeus sometimes were referring to were not the nutty seeds that he had thought, but rather pericarpia that have since been regarded as achenes or caryopses (Lindley 1832).
The usage of the term nut specifically for a name of a fruit type, or pericarpium, originates from Gaertner (1788) who defined nut—"est conceptaculum durum, quod vel plane non dehiscit, vel si aperitur, nunquam in valvulas duabus plures secedit” (a hard conceptaculum, which is plainly not dehiscent, or if opening, never by two or more valves). Although he defined nut as a type of pericarpium (conceptaculum), his descriptions of genera and species sometimes included more than the pericarpium—such as the hard accrescent sepals of Trapa, or the perigynium of Carex for which he also added that the covering in Carex was really an involucre and not a true pericarpium. Nut in Gaertner (1788-1792) was also exemplified by pericarpia with a differentiated endocarp as in Semecarpus anacardium, but species with an undifferentiated pericarpium could also be a nut such as seen in his descriptions of Cyperaceae and other taxa, the pericarpia of which would be regarded as achenes by many modern botanists. In the case of Semecarpus, the term fruit (fructus), rarely appearing in his standardized format for species descriptions, was mentioned in his description as being part of the receptacle; thus, it seems that a separate distinction was being made between pericarpium and fruit of Semecarpus. Similarly, fructus was added in the description for the cone of Juniperus, also referred to as a galbulus, and under his heading of pericarpium for Juniperus was reference to it as a nut, which botanists today would consider an integument. The fruit of Boraginaceae, generally characterized in modern literature as consisting of four nutlets (in Spjut 1994 as a microbasarium of 4 mericarps), was regarded by Gaertner (1788) as a pericarpium of four nuts.
Thus, Gaertner’s (1788-1792) concept of fruit and pericarpium (based on the definitions he presented in his introduction) as applied to the term nut—in his descriptions of genera and species—was not always consistent; however, Gaertner (1788) had indicated fruit can include whatever combines with the mature pericarpium, which he defined as special name for fruit (“Pericarpium, est speciale nomen fructus, que non solum determinatus ovarii maturi habitus exprimitur, sed imprimis quoque ejus diferimen a Semine nudo indigitatur. Hine pericarpium generatim dicitur conceptaculum, ex solo ovario maturo formatum, quod semina intra se ita abscondit, ut propria eorundem figura in conspectum venire nequeat, nisi ex ipse conceptaculo fuerint excussa”). Gaertner (1788), in his introduction, indicated fruits can include various floral parts, and that fruits can also be simple, multiple, partibilis (generally schizocarpic), or compound. He further presented an outline of genera according to fruit and seed types based on the number of cotyledons, presence of a pericarp (naked vs covered seeds), position of the pericarpium (inferior or superior), presence or absence of albumen, orientation of embryo, whether of many separate carpels (polycarpous, which could be apocarpous or schizocarpous in Spjut 1994), number of locules, dehiscence (capsular, poricidal, valvular, circumscissle), indehiscence (baccate or drupaceous and whether dry or succulent). In some cases, his descriptions of fruit (a term rarely applied in his descriptions as already noted above) compares with Spjut’s (1994) concept of fruit; for example, the fruit of Castanea Gaertner (1788) was called a compound fruit, and the pericarpium was indicated to be a nut; similarly, the pericarpium and cupule of Quercus collectively were called a glans, and the pericarpium alone a nut.
The meaning of nut sensu Gaertner (1788) was more narrowly defined by Necker (1790) who introduced the term achene—a fruit with a one-layered pericarp containing a seed—in contrast to nut having a two-layered pericarp in which the inner layer was bony. This was in further contrast to drupe defined as a three-layered pericarp in which the exterior layer was membranous, the medial layer was pulpy or fleshy and the inner bony—referred to as a nucleus—equivalent to the term stone.
However, L-C. Richard (1798, 1808) did not accept the definitions of nut by Gaertner (1788) and Necker (1790) as a fruit type. Instead, he defined nut as a stone of a fruit (pericarpium). But Lindley (1819) suggested that the meaning given by L-C. Richard to nut should be applied to the term putamen. On the other hand Lindley (1832) accepted L-C. Richard's (1798) concept of glans as a fruit exemplified by Corylus (hazelnut), Fagus (beechnut), Quercus (oak), which was earlier defined by de Candolle (1813) as a pulpy or starchy fruit with a single locule containing a single seed intimately adhering to the pericarp that is enclosed by an involucre or cupule with reference to the same three genera. This was in contrast to Mirbel (1813) who indicated that only the pericarpium of Quercus was a glans, and gave the name calybium to the fruit of Quercus as one that includes the cupule (Mirbel 1815); it should be recalled, however, Gaertner (1788) had referred to glans of Quercus as a pericarpium with the cupule. As noted below, Radford (1974, 1986) made a similar distinction as in Mirbel (1813, 1815) for the terms calybium and glans, except he (Radford 1974, 1986) reversed the meanings.
Botanists since L-C. Richard (1798, 1808) have added to the confusion as to the meaning of the term nut. Much of the confusion is the result of new terms provided for slightly differing fruit types as well as modifying the meanings to old terms; the most relevant are glans, drupe, nuculanium, nutlet, achene, cypsela, caryopsis, calybium, “stephanuum,” xylodium, and tryma. Definitions of achene, for instance, which had been exemplified by fruits of the Asteraceae (L-C. Richard 1798; de Candolle 1813), were termed cypsela by Mirbel (1813), and what L-C. Richard (1798, 1808) had called a nut—the stone of a pericarpium (fruit)—was called a nutlet in Mirbel (1813). On the other hand, nutlet in de Candolle (1813) was defined as a fruit derived from a superior ovary, in contrast to achene—derived from an inferior ovary. Additionally, Desvaux (1813) substituted the term stephanoum (“stephanuum”) for the meaning given by Mirbel (1813) to cypsela because his definition included more than just Asteraceae fruits, and he also suggested the term xylodium be adopted for what Necker (1790) and de Candolle (1813) had defined as a nut.
Lindley (1832), in his attempt to straighten out the confusion as to what fruit types should be recognized, the terms that should be applied and how they should be defined, did not employ the term nut in his fruit classification—as also Spjut (1994)—mentioned below. His (Lindley 1832) definition for “achenium,” however, was generally similar to that given for nut by Necker (1790) and by de Candolle (1813), and related terms included tryma—defined as a fruit with an endocarpium and indehiscent sarcocarpium exemplified by the walnut; cypsela—defined and exemplified as in Mirbel (1813, fruit of the Asteraceae), and glans—exemplified by fruits of Castanea and Corylus in addition to Quercus. Many of Lindley’s definitions for botanical terms, including fruits, compare favourably with those in modern botanical textbooks (Stearn 1983).
The North American botanist, Asa Gray, who also had a major influence on definitions for botanical terms (Stearn 1983), initially adopted Lindley’s classification of fruits in his first textbook (Gray 1836; Spjut & Thieret 1989), but in his revision of Lindley’s fruit classification (Gray 1842 & seq.) he substituted the term nut for what he (Gray 1836) and Lindley (1832) had earlier defined for glans. The definition of nut by Gray (1842), which had been previously regarded a glans by Lindley (1832) and his predecessors (Gaertner 1788; L-C Richard 1798; de Candolle 1813), continued well into the 20th century in Gray’s botanical manuals; however, it must be noted that Gray’s definition of nut, as he exemplified by Quercus, excluded the cupule. One notable exception is the 6th edition of Gray (1880) in which both nut and glans are distinguished, and where Gray (1880) may have contemplated further revision of fruit types; his rationale for many terms and their meanings are seen in numerous footnotes.
But not everyone accepted Gray's (1842) definition for nut. Masters (1871) suggested “nuts” for a higher level classification term of fruit types that included achene, carcerule, caryopsis, glans and samara; he did not apply the term nut to a specific fruit type. Sachs (1875) indicated either glans or nut can have the same meaning as also the terms achene and caryopsis. In Figuier’s (1869) glossary of terms, nut is defined as “properly applied to the glans, but also to any hard nut-like fruit, as in Carex and Rumex.” Von Marilaun (1895) distinguished nut as a fruit derived from an ovary of more than one carpel in contrast to achene as a fruit derived from a monocarpellary ovary, and that nut can also have a stony endocarp as in Fumaria, which he also called a drupaceous nut, and it can also be multilocular as in Callitriche.
The various meanings for the term nut were also recognized in 20th century botanical literature. Johnson (1931), for example, defined nut as “a hard-shelled fruit arising from the inferior ovary of a syncarpous gynoecium, as the acorn, hazel-nut. Or the ‘stone’ or bony endocarp of some drupaceous fruits arising from inferior ovaries, as the walnut, or of some true fruits, such as the cherry, plum, almond, peach; or a seed as applied to Brazil-nuts or shelled peanuts.” This broad definition by Johnson (1931) attempts to collectively combine all the meanings that have been attributed to nut in the past, but such a broad definition cannot possibly be systematically applied for distinguishing fruit types. Nut defined more by its application in literature than by strict morphological character features is also seen in Judd (1985) who excluded seed types from the definition of nut. Johnson (1931) also defined nutlet as “a small hard-shelled fruit arising from a superior ovary including mericarps. Borages, mints, vervains.”
Radford (1974, 1986), on the other hand, defined nut more narrowly as “a dry, indehiscent fruit with a hard pericarp, usually derived from a 2-or more carpelled ovary” (Radford 1974), or “derived from a one-loculed ovary (Radford 1986 with an illustration of Corylus as an example), while nutlet was a ”small nut” (Radford 1974, 1986). But definitions for two other related fruit terms in Radford (1974, 1986) confuse the meaning he gave to the term nut; these are: (1) calybium (Radford 1974, 1986)—“a hard, one-loculed dry fruit derived from an inferior ovary, as in Quercus,” and (2) “glans (involucre)” —“nut subtended by a cupulate, dry involucre as in Quercus” (Radford 1974, 1986). Thus, calybium has the same meaning as nut (Radford 1986), while glans can be another name when the cupule is seen as part of the fruit. It might be also mentioned that the fruit of Corylus, which was regarded as a glans (Radford 1974, 1986), is similar to the winged nut as exemplified by Carpinus (Radford 1974, 1986), These examples, calybium and glans, nut and winged nut, are also examples of a double standard in fruit nomenclature (Spjut 1994)—whereby the same fruit can have two different names depending on whether one defines fruit as including accessory structures or as a mature pistil without accessory structures, discussed further in the following section.
Spjut (1994), in his comments under achene, indicated that he decided to not use the term “nut” because it has acquired various meanings over time as evident in popular books about “nuts” (e.g., Duke (1989) as well as technical manuals (e.g., Johnson 1931) and in scientific journals (e.g., Judd 1985), which can include seeds as well as fruits (Johnson 1931). In view of the historical confusion over the meanings given to the term nut, especially when botanists continually try find some way to bring them altogether (e.g., Johnson 1931; Judd 1985), it, therefore, seems best to leave the term nut and its varied meanings in the layperson’s realm. Spjut (1994) was not the only botanist to exclude nut from classification of fruit types; Lindley (1832, 1848), Dickson (1871), Brousse (1880), Wood (1880) and others would seem to have previously decided that achene and/or other terms can be employed with less confusion (Spjut 1994).
Many fruit classifications have recognized seed dispersal structures in gymnosperms as fruit types (e.g., Linnaeus (1751, fructifications [strobilus]; Gaertner 1788–1792, conus, strobilus, galbulus; Desvaux 1813, arcesthida; de Candolle 1813; Lindley 1832, Gray 1880), however, modern day botanical textbooks generally exclude the gymnosperms because the concept of fruit is closely tied to the evolutionary concept of the carpel (Gibson 1909; Foster & Gifford 1974), a term of Greek origin which means fruit, introduced by de Candolle (1813, “Carpon”). The realization that angiosperm seeds are covered by a pericarp (L-C. Richard 1808, 1811; de Candolle 1813) also seems to have led botanists to define fruit strictly as a mature ovary or pistil (Gaertner 1788, pericarpium; L-C. Richard 1798; Lindley 1832; Sachs 1875; Radford 1974; Judd 1985), herein regarded as the pistillate concept of fruit (pistil includes the style[s] and stigma[s] that may persist in fruit). Many common pericarp terms date back to Linnaeus (1751, e.g., capsula, siliqua, legumen, folliculus, drupa, bacca) for which numerous examples were described and illustrated by Gaertner (1788–1792), but it might be noted that Gaertner (1788-1792) still recognized angiosperms to have naked seeds in contrast to covered seeds (by a pericarpium).
The pistillate concept of fruit has many problems in defining and classifying fruit types, especially when accessory parts are fused with the pericarp as exemplified by the pome (Linnaeus 1751) and pseudodrupe (Willdenow 1811; Radford 1974), which have also been classified as “accessory fruit” (Gray 1880; Johnson 1931, Pool 1929; Radford 1974), or “false fruits." This may include any fruit derived from an inferior ovary regardless of whether a change occurs during post fertilization (Johnson 1931).
Botanists who insist on narrowly defining fruit in terms of the pericarp have tried to circumvent this problem by allowing for the inclusion of extraovarian structures in their definition of fruit by simply stating that a fruit is strictly the ripened pistil (or ovary), while it may also include any other parts that have fused with it (e.g., Gaertner 1788; Lindley 1832, Judd et al. 2002), a definition that Spjut (1994) regards as a double standard. Furthermore, what is clearly fused, or what is distinctly separate, becomes problematic (Judd 1985). Additionally, the argument for excluding gymnosperms from fruit classifications makes sense only if the fruit can be defined as a mature ovary (sensu Gaertner 1788, “pericarpium”; Lindley 1832. etc.); i.e. to link it with the evolutionary development of the carpel.
The idea of restricting the concept of fruit to the angiosperm carpel, which may be apocarpous or syncarpous (pistillate), seems to have been advanced during the 20th century (Spjut 1994). An example of an argument made for excluding gymnosperms from the concept of fruit can be found in Gibson (1909). He suggested that the carpel is “the basis of the “true fruits” “defined as a modified sporophyll—containing a seed or seeds,” that “strobilus and galbulus (a short cone),” which “appear as types of fruit in some classifications,” “not only are unnecessary but neither name represents a fruit in the Angiospermic sense.” “To include them in a scheme of fruit classification is on a par with the wedging of the Coniferae in between the Monocotyledons and Dicotyledons in such publications as the London Catalogue and many Floras.” He further stated that “it [is] difficult to appreciate the reasons for the continuance of this archaic classification in floras so modern as Groves’ Revision of Babington’s Manual of British Botany, or lists like that of Britten & Rendle.” Gibson (1909) did not define fruit itself, but among 21 different kinds that he did define are etaerio, cynarrhodon, pome, glans, balausta, and tryma. His concept of fruit, therefore, is one that is a triple standard; on one hand he sees fruit as a product of the flower (or mature gynoecium), a concept that dates back to Tournefort (1694, product of a flower), while on the other hand his definitions for fruit types were restricted to the pistillate concept (Gaertner 1788, pericarpium; L-C. Richard 1798, 1808; Lindley 1831, pericarpium), but he also adopted terminology that his predecessors had defined as including accessory structures.
As an example, Gibson (1909) defined cypsela as a “one-seeded bi-carpellate fruit derived from an inferior ovary.” The term originates from Mirbel (1813) who included the Asteraceae pappus in the definition. Gibson (1909) further added that “[t]his is really a bi-carpellate capsular fruit whose seeds are reduced to one and is physiologically an achene.” As another example, glans was defined as “an achene formed from a capsule by reduction in the number of seeds and abortion of carpels” (Gibson 1909). These examples also demonstrate how botanists attempt to define and employ fruit terminology in a manner that might convey natural relationships. Unfortunately, familiar terms such as berry, drupe and capsule, whose meanings are generally understood and widely employed, are also recognized to occur across a broad spectrum of angiosperm taxa that do not necessarily exhibit natural relationships (Judd 1985; Spjut 1994).
Gibson (1909) further argued that special fruit terms have been given for Morus or Bromelia “aggregates of berries” (“sorosis”) but not for the capitulum of a sunflower in fruit. He suggested that the “polythalamic fruits” be excluded, leaving then only “true fruits” (defined in Johnson 1931 as a fruit derived from a superior ovary) and “pseudocarps” (fruit derived from an inferior ovary). The emphasis on the pericarp in defining fruit (“true fruit”) is further evident in Johnson (1931), who, in distinguishing “true fruits” (derived from a superior ovary) from “false fruits” (derived from an inferior ovary) further recognized that a “false fruit” can also be partly true. For example, he (Johnson 1931) stated “[i]n the mulberry there is a further feature to be observed, namely, that it is the persistent calyx of each flower that forms the succulent part of each fruitlet, while the fruit proper, a true fruit, is completely invested by the calyx and is of the nature of the achene.” Thus, not only do we have true fruits and false fruits, but we also have true fruits developing within false fruits as earlier suggested by Sachs (1875) for the strawberry, regarded as a “pseudocarp, the axial part (or receptacle) of the flower swelling out and becoming fleshy, and bearing on its surface the true small fruits.”
The emphasis on the angiosperm fruit being entirely a product of an individual ripened ovary was discussed in more detail by Egler (1943). “A fruit… as accepted generally by botanists—is a ripened ovary (not gynoecium), or several flowers, together with modified adjacent tissues, separating as a unit at maturity. By this definition each separate unit of the gynoecium (or of a complex of gynoecia!) becomes at maturity one fruit. To exemplify the lack of relationship to one flower: (a) one flower that possesses a compound ovary of united carpels develops one fruit, e.g. tomato (b) but one flower that possesses several separate carpels develops an aggregate of several fruits, i.e., ‘the aggregate fruit’, e.g., strawberry; while (c) a flower cluster of many flowers develops one fruit, i.e., the ‘multiple fruit’, e.g., mulberry. The essential characteristics of a fruit so defined are therefore: (1) its origin from ovarian material and accessories’ and (2) its separateness at maturity. This circumscription of the concept of fruit has been used so long and is found so generally in current taxonomy textbooks that extra effort must be made to realize its unusually arbitrary and illogical nature. It represents a curious attempt to combine in one definition both the concept of fruit of the analogously comparable dissemination units of the plant and the homologously comparable reproductive units, with result that are often inconsistent, self-conflicting, and disastrous to the best expression of each concept.” Because Egler (1943) indicated that botanists will not easily give up the concept of fruit as a product of a pistil, he suggested the term fructus be adopted for any disseminating fructification composed of more than just one mature pistil, and that the term fruit be applied to what botanists have been trying to accomplish for centuries (be limited to the pericarpium). But fructus (Latin) means fruit so Egler’s proposed term (fructus) is really the same old term (for fruit) in disguise.
This is in contrast to Spjut (1994) who, on the other hand, suggested that the older term pericarpium be applied to the individual mature ovary (e.g., Linnaeus 1751; Rose 1775; Gaertner 1788; Moench 1794; Link 1798; Willdenow 1811; de Candolle 1813; Barton 1827, 1836) and that fruit be defined as it has been (applied) for centuries—one that can also have accessory structures to the pericarpium as a dispersal unit of one or more seeds. Furthermore, Spjut (1994) realized that by recognizing various anthocarpous fruits there is no longer any justification for limiting the concept of fruit to just angiosperms. Nonetheless, botanists will continue to find some way to have their fruit cake and eat it too—as they have been doing for the past several centuries—in applying a double standard to defining and classifying fruit types (Spjut 1994), as also exemplified by the contradictory nature of names given to fruit types, e.g. indehiscent capsule (Radford 1974), dehiscent drupe (Judd 1985).
As an alternative to the pistillate concept, it has also been suggested that fruit be defined as a product of the gynoecium (e.g., Tournefort 1694, Vines 1895; Gusleac 1939; Knoll 1939; Winkler 1939; Egler 1943 [“Fructus”]; Foster & Gifford 1974); however, accessory structures are still technically excluded even though they may be seen as part of the fruit, and they may even be employed in the classification of fruit types (e.g., Winkler 1939; Ullrich & Arnold 1953). Gray (1880) defined fruit as "the matured pistil or gynoecium (as the case may be), including also whatsoever may be joined to it," while Henslow  had defined pericarpium as “the ripened condition of the ovary or ovaries, and any externally adhering appendages of the flower, in contrast to his broader definition of fruit to include "any appendages of the inflorescence which may accompany them, and seem to form an integral part with them.” Many 20th century authorities opposed the idea that fruit include more than the gynoecium, which would obviously exclude gymnosperms (Gibson 1909; Gusleac 1939; Foster & Gifford 1974; Knoll 1939; Ullrich & Arnold 1953; Winkler 1939). Egler (1943), in a footnote, stated that his attempt to define fruit to include accessory structures met with so much misunderstanding and opposition that he finally conceded and proposed the term “fructus” instead. He (Egler 1943) further suggested another term for collective gynoecia in fruit, “fructus cluster” (compound fruit, Spjut & Thieret 1989; Spjut 1994). Nevertheless, the definition of fruit has been more recently stated by some to explicitly include extra-ovarian or extra-gynoecial parts; Cronquist (1961), for instance, defined fruit as “the ripened ovary, together with any other structures that ripen with it and form a unit with it.”
From the foregoing discussion, fruit, even in its narrowest definition, is recognized to be composed of one or more seeds that at the time of dispersal are usually accompanied by megasporophylls (which can be evolutionary modified carpels), while in application its accessory structures may also be recognized as part of the fruit, e.g.“false fruits.” If the so-called “false fruits” can be recognized for angiosperms, why not for gymnosperms? They too have seeds and megasporophylls that can include accessory parts. Actually, Beck (1913) recognized the gymnosperms as Spermatocarpia and the angiosperms as the Eucarpia, classification terms that were adopted by Spjut (1994). Moreover, Spjut (1994) stated that “it is not uncommon to find in contemporary literature a gymnosperm cone being referred to as ‘fruit,’ for example, the USDA Forest Service Silvics of North America (1990) refer to seed cones of Taxus as fruits, while they also refer to the fruit of Alnus as a cone. As already indicated elsewhere on this site, it is seeds that are being dispersed for reproductive purposes, not ovaries; a similar statement was made long ago by Marilaun (1895) who also recognized gymnosperm fruits: "in the broad sense fruit in Phanerogams should include everything which undergoes alteration after fertilization either in the flower or flowering axis. All of these changes take place in parts in question for the purpose of promoting the interests of the embryo, and properly equipping it when the time comes for its severance from the parent plant, consequently the whole of the structure which participate in this object should be regarded as the fruit.”
The fruit is not just an end product by itself; the classification and determination of its types require study of its entire development from the time of fertilization. As Schleiden (1849), stated “the fruit is merely the final result of a series of developments of the whole plant, the last product of a great number of factors, and gives no conclusions about what has gone before, about the number and nature of the co-operating factors.” One cannot expect to discern fertilization; however, one may determine the changes that have occurred by comparing the construction and arrangement of flowers, or megasporophylls, with fruit.
Despite Gray’s (1880) criticism of Dumortier’s (1835) phytography, Spjut (1994) adopted Dumortier’s nomenclatural framework for many pericarpial terms. He also applied the same concept in terminology to anthocarps setting a new precedent, and further recognized many new types of compound fruits (those derived from more than one flower), especially in the Poaceae, which included a whole new “series” he named Anthecocarpi. Obviously, this is a radical change from current teaching, and somewhat overwhelming in that 95 different kinds of fruits are recognized. Yet, when one really looks at the wide variation in fruit morphology, one wonders if not more terms should be used. Spjut (1994) reviewed fruits of ~1100 genera, perhaps only 7% of the number of genera of seed plants (~15,000). What taxonomists need to realize is that additional revision might be expected as more genera are studied.
Identification of fruit types is not an exact science. Rather, it is complicated by the enormous morphological diversity of fruits that can be seen for just one type, while also having to recognize that similar mechanisms of dispersal have independently arisen in many unrelated taxa. It is also tedious in that it requires careful consideration not only to the changes from flower to fruit, but also to the detail of the differentiation of fruit layers, texture, and dispersal of seeds. The classification of fruits is also frustrating in having to deal with both natural and artificial criteria.
Many will argue that seed cones of gymnosperms should not be considered as fruit types because gymnosperms do not have seeds enclosed in carpels, although seeds in the Gnetales are interpreted by some to be enclosed by a perianth. The argument by Spjut (1994) is that fruit often includes more than just carpels, and one must keep in mind that it is seeds that are being dispersed, not just the ovaries or carpels, necessarily. Indeed, the presence of accessory structures in fruit is more often the rule than the exception (Spjut 1994).
An example is the fruit of Physalis (Solanaceae) that Spjut (1994) regarded as a diclesium because of development of a fruiting (accrescent) calyx, in contrast to Judd et al. 2002 who regarded the fruit of Physalis heterophylla as a berry, while noting the presence of an accrescent calyx (Judd et al. 2002, illustration of Physalis heterophylla captioned “flowers and fruits,” Fig. 9.121-A, and “berry and calyx in cross-section,” Fig. 9.121-H). The fruit of Solanum was also cited as an example of a berry, a fruit that does not include the calyx (Judd et al. 2002). Thus, they apply the same term to two different kinds of fruits. Their definition of fruit is one that is “a matured ovary along with fused accessory structures” (Judd et al. 2002); but, as evident from the foregoing examples, they distinguish fruit types based solely on the pericarp (except for drupe and pome). This practice dates back to Lindley (1832) who defined fruit as “the ovarium or pistillum arrived at maturity; but, although this is the sense in which the term is strictly applied, yet in practice it is extended to whatever is combined with the ovarium when ripe.” It would seem, therefore, that botanical textbooks have changed little over the past 170 years—in applying a double standard to defining fruit and naming its types.
On the other hand, Judd et al. (2002) encourage the use of modifiers to established fruit terms such as “arilloid berry” for the fruit of Litchi (Sapindaceae), instead of just referring to it as a berry. Stuppy and Spjut (in prep.) propose to apply more descriptive modifiers to established terms, essentially a binomial nomenclature for fruit types. For example, the fruit of Physalis may be regarded as baccoid diclesium. By adding the modifier “baccoid” to diclesium, we hope plant systematists will find baccoid diclesium a more acceptable name for the fruit of Physalis heterophylla instead of having to choose, for example, between berry (Judd 1985, Judd et al. 2002) and diclesium (Spjut 1994). Also, by applying such binomial names, other diclesia such as nuculoid diclesium (e.g., Corylus) and drupoid diclesium (e.g., Bucida) can be more easily envisioned without having direct knowledge of the floral morphology of a genus. Other descriptive methods for clarifying the differences between fruit types can be found in Spjut's (1994) introduction.
It might also be noted that cones of gymnosperms are often interpreted from an evolutionary point of view rather than from a dispersal point of view (for fruit classification purposes). For instance, the fleshy structures that surround the seeds of Taxus, Torreya, Cephalotaxus, Amentotaxus and Austrotaxus are not homologous even though Spjut (1994) regarded them as an arillocarpium. In Amentotaxus, there is an integument and an outer aril layer, which are mostly fused; in Torreya. the integument may be further differentiated as having a bony layer, and the seed of Cephalotaxus has been interpreted to include three outer layers (integuments) and a rudimentary aril at the base. Additionally, in the Gnetales, the fruiting megastrobilus (compound cone) of Gnetum resembles an infructescence of angiosperms, while the dispersal unit is the seed with integument and additional bracteate layers, the outer of which may be regarded as perianth and the inner hardened, thus, the fruit appearing drupelike. The fleshy fruited ephedras have additional lower sterile scales, which are connate at base, and which loosely envelope the seed(s), described as a fleshy false berry in the Flora of USSR, which corresponds to arcesthida; however, in the dry ephedra cones, the seed dispersal unit may be referred to as a galbulus.
There are many variations in seed dispersal for gymnosperm cones that deserve distinction as fruit types than what is currently recognized in Spjut (1994), particularly in regard to dehiscent cones and schizocones that were all included under compound cone. These are under review by Stuppy and Spjut (in prep).
A nomenclatural system for distinguishing the different kinds of fruits is necessary; however, as previously indicated, in order for a nomenclatural system to be successful in naming fruit types, it will also be necessary for a "group of botanists" sufficiently representative that their colleagues may be ' disposed to accept' the results" (Rickett 1954) such as the Systematics Association Committee for Descriptive Biological Terminology (Anonymous 1960, 1962).
To have credibility, this requires procedures for which fruit terms and their definitions can be recognized. As it stands, the meanings of carpological terms are a matter of "usage", and when the meaning to a term is confused, a clear meaning must be adopted by agreement (Rickett 1954). But the idea of standardising a large number of carpological terms and their meanings might run into rejection as in the case of protecting names of plants in current use that was proposed at the 1999 Saint Louis International Botanical Congress (Greuter et al. 2000). Nevertheless, it is not advantageous to continue working with confused meanings of many carpological terms until they pass a history test of "usage." A procedural basis could be set up through the ICBN such as one similar for proposing to conserve names. Meanwhile, the following guidelines are proposed to establish carpological terms and their meanings.
1). Terms employed as names for fruit types, or for descriptive features of fruits, should be independent of those in use for describing other plant organs.
Example 1A: Compound, leaf, compound cone, compound ovary, and compound fruit have meanings that are not homologous; compound ovary, for instance, defined as a gynoecium of united carpels (to form a single compound pistil) does not necessarily mean that it has to produce a compound fruit of the same structure (Linnaeus 1751; Spjut & Thieret 1989); a compound fruit is one formed by the coalescence of ovaries in an inflorescence that occurs during maturation to form a single fruit composed of many pericarpia.
Example 1B: The definition of fruit in angiosperms does not mean it has to be homologous with the seed-scale complexes in gymnosperms, but it is a seed dispersal structure in which seed is viewed as monophyletic, while parthenocarpic fruits are also recognized.
2). Carpological terms begin with those in Linnaeus' Philosophia botanica (1751).
3). The meaning of a carpological term should not be redefined so as to exclude its original meaning.
Example: 3A. Ceratium was originally defined by Lindley (1832) as a "one-celled, many-seeded, superior, linear, dehiscent by two valves separating from the replum; seeds attached to two spongy placentae adhering to the replum," as represented by Papaveraceae genera Glaucium, Corydalis and Hypecoum. It was adopted by Spjut (1994), and given a much broader meaning with represenative examples from 20 families based on Cronquist (1981), which included Proboscidea althaeifolia (Martyniaceae). Barroso et al. (1999) redefined the term, limiting its application to just Proboscidea althaeifolia, and by doing so they excluded the original meaning given by Lindley (1832). The meaning given by Barroso et al. (1999) should be disregarded.
4). New carpological terms should be created only after consideration to previously established terms as found in references provided by the Systematics Association Committee for Descriptive Terminology (Anonymous 1960), by Spjut and Thieret (1989) and by Spjut (1994). Exceptions may be allowed through an established international committee of botanists who agree by simple majority (>50%).
Example 4A: Hertel (1959) coined the terms Eucarpo, Paracarpo and Teleocarpo that are equivalent in meaning to simple, multiple and compound, respectively, in de Candolle (1813) and Gaertner (1788), which were reviewed by Spjut and Thieret (1989). Therefore, Hertel's terms should be considered least preferred.
5). Where there is a choice between two terms with similar meanings, the one with the longer established use should be chosen except when new or later terms can be justified to have greater mnemonic, didactic, and/or phonetic attributes.
Example 5A: Microbasarium from microbasis of de Candolle (1813, 1819) has no evidence of use other than by de Candolle and Desvaux (1813) before it was adopted by Spjut (1994) and Barroso et al. (1999). Subsequently, there is little evidence of its application outside these references, and because it has no relational value to other carpological terms in Spjut (1994) or Barrosoa et al. (1999), a new proposed term, bilomentarium (Spjut & Stuppy in Stuppy & Spjut in prep.) is clearly a more fitting and appropriate with respect to the other previously established terms: bilomentum, and lometum and lomentarium (Spjut 1994).
6). Terms with a long history of confused meaning should be avoided.
Example 6A: Nut as applied to a fruit type has been ambiguous in meaning since Linnaeus (1751), as well as before Linnaeus. The term has been employed to describe hard seeds, hardened parts of the pericarpium, hardened accessory structures to pericarpia, or collectively any combination of these as a fruit type. It can be employed to express this broad general meaning, or for any part of a fruit, but as a name for a specific type of fruit, it is not suitable (e.g., fruit of Quercus), especially when other terms such calybium, glans, xylodium, achene, cyspela are available. Exceptions may be made through an established international committee of botanists who agree by simple majority (>50%) as to how such terms as nut should be defined as a fruit type.
7). Terms should not coincide with generic names of plants as stated in the ICBN (Art. 20.2, except for those published before 1 January 1912, provided that that the genus name was accompanied by a species name).
8). Terms should not be applied in contradiction to their meaning.
Example 8A: Indehiscent capsule, where indehiscent means that a fruit does not open at maturity, and capsule that is defined as a fruit does open at maturity.
9). Terms should be defined to have a clear and specific meaning.
Example 9A: Gray (1880) defined fruit as one that "consists of the matured pistil or gynoecium (as the case may be), including also whatsoever may be joined to it." "It is a somewhat loose and multifarious term, applicable alike to a matured ovary, to a cluster of such ovaries, at least when somewhat coherent, to a ripened ovary with calyx and other floral parts adnate to it, and even to a ripened inflorescence when the parts are consolidated." Gray thus admits that the term fruit does not have a clear meaning. But a precise definition is essential to defining fruit types. Gray's definition does, however, convey the variable meanings that have been applied to the term fruit before and since 1880. Gray's (1880) definition also did not exclude gymnosperms as they were regarded to have "open pistils" (Gray 1887).
10). Terms should be consistent in meaning and in application with other carpological terms.
Example 10A: Fruit should not be defined as a mature ovary and then its different types be recognized to have extra-ovarian ("accessory") parts.
Example 10B: Multiple fruit and aggregate fruit have a long history of confused meanings. Multiple means to increase or multiply (Brown 1956); aggregate means collected or united (Brown 1956). Multiple fruit and aggregate fruit were first defined together by de Candolle (1813); multiple for fruits derived from an apocarpous gynoecium in which the fruiting carpels are distinct, and aggregate for fruits derived from an inflorescence in which fruiting carpels and other floral parts come together at maturity to literally form an aggregate (Spjut & Thieret 1989); de Candolle's application is consistent with the meanings in Brown (1956). However, many English language text-books teach the wrong (reversed) meanings to these terms that dates back to Lindley (1832), whose definitions for these fruit types contradict the literal meanings of the terms themselves. One may argue under Rule 5 (above) that a long historical usage dictates that this incorrect trend continue; however, nonEnglish authorities in France, Germany, Russia, and Brazil have followed de Candolle (1813). Moreover, Takhtajan and Kaden (1963) also recognized multi-achene and multi-follicle as fruit types under multiple fruit. Spjut and Thieret (1989) who reviewed this matter in detail recommended that multiple in sensu de Candolle (1813) and that an earlier term, compound fruit, sensu Gaertner (1788), be adopted instead of aggregate sensu de Candolle (1813) to avoid further confusion and to allow for consistent meanings with other carpological terms (e.g., multi-achene).
11). Authors should avoid presenting alternative terms for the same meaning.
Example 11A: Asa Gray (1880) frequently presented two choices for the meaning of a fruit type—Accessory or anthocarpous fruits, multiple or collective fruits, strobile or cone, pepo or gourd fruit, drupe or stone fruit. Only one term is necessary in each case. Synonyms or alternate terms may be given in parenthesis, e.g. bilomentarium Spjut & Stuppy (microbasis de Candolle 1813, 1819).
12). Proposed meanings for new terms should include examples by reference to genera and species and one should be chosen as best representative or most typical (e.g., see Spjut 1994).
13). Names for fruit types can be either monomial or binomial. Trinomials or longer strings of text are to be treated as descriptive text rather than as a name for a fruit type.
Example 13A: Aggregate accessory fruit was defined by Cronquist (1961) as a name for a fruit type [exemplified by the rasperry (Rubus idaeus L.), blackberry (e.g., Rubus canadensis L.) and strawberry (Fragaria) = drupeteum or glandetum (Fragaria) in Spjut 1994], is to be treated as a technical description for a fruit. Examples of terms intended to be employed for describing rather than naming fruits can be found in Shultz-Shultzenstein (1864); Germain de Saint Pierre (1869), Winkler (1939, 1940), Egler (1943), Baumann-Bodenheim (1954), and Levina (1961).
14). New names for fruit types should be clearly designated by novum (or nov.).
15). Names for fruit types accompanied by a change in meaning or applied in combination with another term should be indicated by emendatus (emend.) or modificatio novum (mod. nov.).
16). When two or more names for fruit types are combined, or when a name for a fruit type is split into two or more fruit types each with different names, the species that originally represented the name for one of the fruit types must be retained as representative (typical).
Example 16A: Bibacca of Beck (1913), adopted by Radford (1974) and Spjut (1994), may not the most appropriate name to apply to other fruits of similar derivation that differ in pericarpium type; the pericarpium of Mitchella repens, for example, is a drupe. Rather than apply a different prefix, another term in Beck (1913), dicarpium ("dicarpia"), represented by Didymanthus roeiI, may be adopted. The different dicarpia can be better distinguished by common modifiers such as baccoid dicarpium (e.g., Lonicera), drupoid dicarpium (e.g., Mitchella), and utriculoid (typical) dicarpium (Didymanthus). The latter, represented by Didymanthus roei, is considered most typical of the dicarpium as indicated by Beck (1913). Consequently, bibacca is still typically represented by Lonicera tatarica L. (Spjut 1994) while also regarded as a synonym of a baccoid dicarpium. The modifiers based on pericarpium types are preferred over the prefix bi (e.g. bibacca, bidrupa) for consistency in terminology to a specific fruit classification (Spjut & Stuppy in Stuppy & Spjut in prep.).
17). Determination of a fruit type is based upon the parts that form the bulk of the dispersal structure, which includes the seed(s).
Example 17A: The Malus apple is largely derived from hypanthium; therefore, the most appropriate name for the structure as a fruit type is a type of anthocarp (pome); it is not to be based upon the type of pericarpium (carcerulus). In the case of fruits derived from an inferior ovary where the perianth does not appear to be accrescent, or it is difficult to differentiate the two, the pericarpium is the determinate basis for the name of a fruit type.
18). The presence of vestigial accessory structures do not necessarily decide the fruit type unless delineated by its key attributes.
19). The basic types of pericarpia, which may also be employed as modifiers, are: (1) camara, (2) follicle (follicular), (3) coccum (coccoid), (4) achene (achenoid) (5) carcerulus [nucoid], (6) berry (baccate, baccoid), (7) drupe (drupaceous, drupoid), (8) capsule (capsular), (9) samara (samaroid), (10) utricle (utricular) and (11) lomentum (lomentaceous, lomentoid).
20). Authors who use a nomenclature system for designating fruit types by name, as opposed to employing terminology to describe fruits in detail, should provide reference(s) to substantiate the descriptive characteristics that apply (to the name for a fruit type).
Calamus (Arecaceae). The fruit of this genus is not a glans; it has has a thin pericarp with reflexed epidermal scales (epicarp), usually dehiscent, sometimes irregularly between the scales, and contains 1–3 seeds having thick sarcotestas. The irregular dehiscence suggests a foraminicidal capsule.
Sorosus. The definition of sorosus (= sorosis = coenocarpium) is amended here as follows: A compound fruit in which pericarpia are fleshy and develop on a peduncle, or are enveloped by an accrescent fleshy perianth (Jan 2008).
Page 150: Reference to the fruit of Cakile maritima Scop. (Brassicaceae) should be bilomentum, not lomentum.
The fruit of Musa × paradisiaca, referred to as a pepo is derived from an ovary with axile placentation, while pepo is defined as a fruit with parietal or apical placentation. This is also in contrast to the hesperidium with axile placentation. The banana (Musa × paradisaca) is mostly aseptate as also the fruit of Musa banksii, illustrated in Fruits of the Australian Tropical Rainforest by Wendy Cooper and William Cooper (2004), while an illustration in the Flora of Taiwan for M. formosana shows a septate fruit. The definitions should emphasize the presence or absence of septa in fruit rather than placentation.
Page 88. Poricidal Capusle: Poricidal dehiscence should include reference to Gaertner (1788) who also described the dehiscence as foramine dehiscens for Heuchera americana, Baeckea imbricata, Hydrangea arborescens, Roella ciliata, Jasione montana, Phyteuma spicata, Trachelium caeruleum, Campanula rapunculus. The fruits appear to include ceratium, denticidal capsule, foraminicidal capsule as well as poricidal capsules.
Page 93: The fruit of Quiina indica appears to lack endocarp development as described in literature and from web photos appears to be an utricle. (12 Dec 2010).
Page 104. Under Pseudosamara, Tilia. It is suggested that he compound form of this fruit be regarded as a pseudosamarosum, a fruit type that has not been formally recognized.
Page 130. Circumscissile Capsule: should also include reference to Gaertner (1788) who described the pericarpium of Sphenoclea zeylanica as circumscissa (dehiscence) with an operculum.
Pages 83 & 137: Glans, L-C. Richard (1798) should be replaced by Gaertner (1788). Gaertner (1788) in his caption for an infrutescence showing three glans of Quercus robur indicated "Glandes aggregatae" on a long peduncle.
Graziela M. Barroso, Marli P. Morim, Ariane L. Peixoto, and Carmem L. F. Ichaso. 1999. Frutos e sementes. Morfologia aplicada a sistemática de dicotiledôneas. Editora UFV, Univesidade Federale de Viçosa, MG, Brasil, 443 pp., including 234 numbered figures, each figure with 6–12 or more illus, 15 plates in b/w, each with 6 photos.
This is a tremendous compilation on the taxonomy of tropical fruits and seeds in which the authors recognize 52+ fruit types for the dicot genera of Brazil. The leading author, the late Graziela Maciel Barroso (1912–2003), was a notable authority on the flora of Brazil, having published a three-volume work on the “Sistemática de Angiospermas do Brasil.” In comparison to the treatment by Spjut (1994), who recognized 95 different fruit types, Barroso et al. (1999) made a greater distinction among follicular, capsular and baccate fruits, while not clearly recognizing anthocarps (except “velatidium”) or compound fruits; however, inconsistencies appear in the captions to illustrations that suggest such terms were considered; in Fig. 14, for instance, the fruit of Mirabilis sp. is described as a “nucúla con antocarpo” and fruits of Moraceae are referred to as “composto.” On the other hand, they clearly accepted simple fruits and multiple fruits sensu Spjut & Thieret (1989) and Spjut (1994), but without further distinction as to types, although subdivision names are evident; e.g., fruto múltiplo cupuliforme” for accessory structures that aid in dispersal of the fruit, corresponding to Discocarpi of Spjut (1994). Their emphasis was on differences in monomerous vs. syncarpous gynoecia, pericarp texture, placental types, and dehiscence patterns for which most names were given only in Portuguese; however, for this review I present them in a more familiar Latin or English format, including corrections for spelling errors (e.g., cerastium should be ceratium). In the Fabales, the fruit types include follicle, legume, lomentum, craspedium, samaroid legume, cryptosamara, cryptolomentum, sacellus, drupoid lomentum, baccoid lomentum, and nucoid lomentum. The first four terms (follicle, legume, lomentum, craspedium) were employed by Spjut (1994) who also recognized a faboid follicetum. Loculicidal capsule was a heading term for many capsular types that included loculicidal, rimosa, ruptile, follicular, ringentas, circumdantas and bertolonidium. Another was capsula tubulosa for those that dehisce incompletely, irregularly or are surrounded by perianth, and this included their capsula rompente, velatidium, capsula lobata, capsula dentada, capsula septifraga, siliqua (including silicula), poricidal capsule, circumscissile capsule, and ceratium. They also recognized schizocarps such as the microbasarium, regmidium, samaridium, and cocas. The remaining fruit types were classified under nucoid (samara, betulidium, achene, nucula and nucoid), drupoid (drupa, nuculanium, pilotrymidium), and baccoid (hesperidium, balausta, melonidium, peponidium, solanidium, campomanesoidium, amphisarcidium, baccidium, baccaceous, theophrastidium, pomidium).
Their names and definitions for fruit types have little in common with their predecessors, except in Brazil where they incorporated some of the ideas of Hertel (1959), Baumgratz (1985), Schoenberg (1976), and others. Indeed, there is no mention of Linnaeus (1751), Gaertner (1788–92), de Candolle (1813), Mirbel (1813, 1815), Desvaux (1813), Dumortier (1835) or Lindley (1832, 1848). The only mention of Spjut (1994) was in regard to his omission of cryptolomento in Burkart (1943), and that fruits treated in his study (Spjut 1994) were found mostly outside of Brazil; thus, the foundation work that Spjut had developed was largely ignored, except, however, for a few terms such as ceratium and microbasarium that were adopted, but with almost entirely new meanings.
The book has an awkward landscape page orientation that I found difficult to use in which the pages are wider than tall. Another problem I had—in trying to learn their concepts of fruit types—was with examples of the same fruit type appearing in different sections of the book, because the authors also present fruit types by family and by genus; there are keys to the different fruit types; there are keys to families that have a certain kind of fruit, and there are also keys to genera within families based on fruit and seed morphology. In the discussion of fruit types, examples are referenced by figure numbers without mention of genera or species names; therefore, the reader has to thumb through the pages to locate the figure where the genera and species are mentioned in regard to their descriptions of fruit types. The family/genus keys are arranged in a phylogenetic format by family as opposed to an alphabetical one. The objective, obviously, is to identify any dicot plant from Brazil to genus based on fruit characteristics.
The authors are to be commended for providing many illustrations of fruits of Brazilian plants, and for the keys to the dicot genera of Brazil based on fruit characteristics. This alone is useful despite the difficulty in organization of the material, unfamiliar terminology, and misapplied meanings to familiar terms. Nevertheless, it would have been helpful if they had referenced their terms and followed the recommendations of Spjut and Thieret (1989) in selecting and defining their fruit types. Had they done so, their book undoubtedly would have greater ease of use among the scientific community.
Cooper, Wendy and William T. Cooper. 2004. Fruits of the Australian Tropical Rainforest. 616 pp with 1230 illustrations, mostly color.: 30 x 23 cm. Nokomis Publications. ISBN-10: 0958174210. Hardcover £151.00 or ~US $300.00 or A $225, plus shipping.
Anyone interested in tropical fruits will want this floristic reference. It is unquestionably one that is in its own class. It is a comprehensive and magnificent work of art and taxonomy combined that illustrates and describes 2,436 species of tropical Australian fruits in 632 genera and 153 families. But it is not the first. An earlier 1994 edition by the same authors, Fruits of the Rain Forest: A Guide to Fruits in Australian Tropical Rain Forests described and illustrated 626 species (reviewed by Rudolf Schmid, Taxon 44, pt. 4, 1995, p. 661). While I have not seen the 1994 publication, this second edition supposedly includes or replaces the illustrations in the earlier book and adds more than 600 new illustrations. The book itself is somewhat massive, comparable in size and weight to that of Brodo, Sylvia and Steve Sharnoff's Lichens of North America. It presents not only known species but in some cases undescribed genera and species; thus, it truly is comprehensive in content.
It is not just a picture book. Descriptions are presented for each species in a standard format that includes not only that of the fruit but also the habit of the plant, leaves, inflorescence, flower, and geographical distribution. This information comes from the authors field work and study of herbarium specimens. Species and genera are alphabetically arranged within families that are also alphabetically arranged, except gymnosperms and angiosperms are separated. At the beginning of each family is a key to the genera, and within each family are keys to species in the genera that have more than one species. A key to the families is presented at the end of the book along with a limited but illustrated glossary. The geographical coverage is also shown by maps near the beginning of the flora. Descriptive information also includes the number of species in each genus and its geographical distribution in the world, in Australia, and in the flora.
Although this book is intended as an identification tool for tropical Australian plants with emphasis on fruit characteristics, it is not necessarily a technical manual. Indeed, the authors state their intent to minimize use of technical terms; I estimate about 240 terms in the glossary. Terms for fruit types are limited to achene, berry, capsule, drupe, follicle, mericarp, multiple fruit, nut, pod, samara, and syncarp.
The fruit illustrations and their layout are artistic in presentation in contrast to the standardized outline format for descriptions. Some take up nearly the whole page while other pages have minimal illustrations. They appear accurate, and are useful in that they often show infructescences, whole fruits, cross-sections and longitudinal sections. The color illustrations are not line drawings but paintings that are so well done that one could easily mistake them for high quality color photographs. Additionally there are black and white line illustrations of leaves for most genera to facilitate identification.
The cost of this book will make one think twice. I purchased mine from a bookseller in Australia and with shipping it ran ~$275. But it is more than cost that will probably limit availability; advertisements indicate only a limited number of copies have been printed. In a way, it is a beautiful piece of art whose value will undoubtedly increase in time, while the scientific value is also immeasurable. Congratulations to Wendy Cooper and William T. Cooper for their unique and immense contribution to tropical botany.
Richard Spjut, February 2007
At first glance this publication might appear to be another one of those color photo books that presents random selection of plants with pretty flowers. But this one differs in that the author provides photographs of the plant not only in flower but also in fruit, supplemented by an illustration on the habit of the plant. Each page is usually devoted to one species that includes a narrative on the economic, medical and/or horticultural value, other interesting information about each species' distinctive characteristics, a narrow separate column in smaller print that briefly describes the characteristics of various parts of the plant in a standard outline, and various size color photos with captions that give more tidbits of information about each species. Occasional pages present mostly color photos and captions. At the beginning of the book are color coded maps on three pages that depicts 12 plant hardiness zones shown for the entire world. The appendix includes an illustrated glossary in painting style as well as terms that are defined without illustration.
Barwick's book is made more useful by the selection of species representative of the more common tropical genera, species that are most likely to be encountered. The author clearly has a broad knowledge of tropical plants. As noted on the jacket, she spent more than 45 years as gardener and landscape designer in New Zealand, the Solomon Islands, Malawi, USA, France, the British Virgin Islands and the Cayman Islands, In my recent expedition to Hawaii, sometimes I could not find an introduced plant in the well-known Wagner, Herbst and Sohmer Manual of the flowering Plants of Hawaii (revised ed. 1999), or even in other books available on Hawaiian introductions, but it was in Barwick's book. There are not many publications that systematically present photographs of fruits along with that of flowers. Barwick's book does that very nicely; her book on tropical plants is well worth its price.
Richard Spjut, March 2007.
Kesseler, Rob and Wolfgang Stuppy. 2006. Seeds. The Time Capsules of Life. Papadakis Publishers, in collaboration with the Royal Botanic Gardens, Kew, with preface by HRH the Prince of Wales, 264 p., full color, 30.5 x 28 cm. £35.00.
This is one of those educational coffee-table books with an unusual artistic quality. Indeed, the art work appears surreal. The purpose of the book is obviously to draw attention to the microscopic world of seed topography and to make us more aware of just how important seeds are in our lives.
Rob Kesseler and Wolfgang Stuppy accomplish this on a grand scale by blowing up SEM photos of seeds that are stunning in their topographical detail; for example, Spergularia rupicola, a plant found along the sea coasts of the British Isles—whose minute seed is normally 0.5–0.7 mm long (Flora Europaea Vol. 1)—takes up one whole page, the seed itself (in the photo) measures out to 23 cm in length, a magnification of ~1,000x. The papillate and contoured surface of the seed is further accentuated by the addition of color. Not all photos are of seeds, however. There are many photos of fruits (e.g., Uncarina), fruitlets (e.g., Hackelia) and fewer photos of inflorescences (e.g., Verbascum) and flowers (e.g., Silene). The book includes a bibliography, a glossary and an index to the species names along with their authors, family names, common names, and origin of the plant used in the photo, and with an additional note on its geographical distribution. Some coffee-table books use white background on text but Kesseler and Stuppy employed various colors for background and text. On some pages text could have been a little larger or bolder, or perhaps a white instead of color background might have helped.
Although I refer to this as a coffee-table because of its size and artistic imagery, there is a great deal of text, or text-book in this publication. Wolfgang Stuppy, the seed morphologist at Kew, does this in an entertaining and educational writing style as seen, for example, by his many catchy subtitles such as “Beauty lies in the eye of the beholder," or "When it comes to sex, angiosperms want it all.” The main chapters are: What is a seed? Seed Evolution; Naked Seeds; Flower Power Revolution; The Dispersal of Fruits and Seeds; Travellers in Space and Time; The Millennium Seed Bank, An Architectural Blueprint, and Phytopia. While one may initially spend an hour or more looking over the photos and their captions, it will take more time to read all of the text. Many teachers, including professors, might find Stuppy's account helpful to their instruction. In fact, the book could be brought to class for students to review. It would also make a good standard reference for libraries. I have already seen examples of Kesseler and Stuppy's photos at airport magazine shops in what is not too surprising, but relatively new, Seed Magazine.
Richard Spjut, March 2007.
Stuppy, Wolfgang and Rob Kesseler. Fruit: Edible, Inedible, Incredible. 2008. Papadakis Publishers in collaboration with Royal Botanic Gardens, Kew. Edited by Alexandra Papadakis. Includes Preface by Ken Arnold (Head, Public Programs, The Wellcome Trust) and Forward by Professor Stephen D. Hopper FLS (Director, The Royal Botanic Gardens, Kew). 264pp. 305 x 280 mm. Hardcover with dust-jacket. Weight: 4.98 lbs. or 2.26 kg. ISBN 9781901092745. Retail Price: £35.00, $54.25.
This is another extraordinary publication—combining the botanical talents of Wolfgang Stuppy and the artistic talents of Rob Kesseler—on an in-depth presentation of the wide variety of fruits that exist. The format follows their earlier book on Seeds. The Time Capsules of Life; see my review above for a more detailed discussion of the general format.
As in their previous masterpiece, Dr. Stuppy lays out a foundation as to what lies ahead. He begins by asking what is a fruit, in contrast to what defines a vegetable? His explanation follows an outline of the evolutionary relationships and the reproductive differences between angiosperms (flowering plants) and gymnosperms (cycads, conifers and gnetophytes [Gnetum, Welwitschia, Ephedra]), and how they relate to ferns. Stuppy's discourse is accompanied by relevant photographs and stunning images by Rob Kesseler. The images are also accompanied by captions. Both captions and text often include intriguing short stories integrated into the detailed discussion on the reproductive biology of seed plants and the dispersal strategies for the various kinds of fruits. This includes fruit names applied as botanical terms, often with a discussion on their confused meanings. The main story, however, is how the concept of fruit itself has become intimately associated with flowering plants to the exclusion of the so-called naked seed plants (gymnosperms), and how this biased application can make it difficult for the angiosperm fruit lovers to provide a scientifically sound definition for the term fruit. The long-time controversy in defining fruit is evident in many of the section titles: “No flower no fruit,” “No carpel no fruit,” “How to be a carpologist,” “Babylonian Confusion,” “Two fruits in one,” “The true meaning of fruits,” “Carpological troublemakers,” “Bogus fruits and how to debunk them,” and finally—“So what is a fruit”? You won’t find a straight answer to the latter question but in the end fruit is defined in the glossary as “any coherent seed-bearing structure, including domesticated fruit bred to be seedless.” This definition obviously does not exclude gymnosperms.
The concept of fruit and its different kinds cover 120 of the first 140 pages. The next 110 pages focus on the various adaptations fruits have evolved for dispersing their seeds (“Dispersal—the many ways to get around”). In this part of the book there are photos of the dispersers as well as of the fruits where one may also see artistic depictions of “frugivores” that are no longer with us such as the “Stirton’s thunderbird,” “one of the largest birds that ever lived.”
The final pages of the book are about the Millennium Seed Bank Project and Rob Kesseler’s artistic approach. Kesseler images are enhanced digital SEM (scanning electron microscope) productions. As explained by Kesseler himself, “Pollen grains are small, many hundreds can be captured in one frame; seeds are bigger, one seed fills one frame. Fruit, even small fruit, by its very nature tends to be much larger, most of it too large to fit in the SEM. The image of the strawberry fruit on the cover of this book is made up of over forty separate frames carefully stitched together, cleaned up, tonally readjusted, and finally coloured, a process taking many long, intensive hours.” “Whereas working in watercolour or pastel is an additive process—building up washes and layers of colour, covering what lies beneath—these images evolve from flat, grey micrographs, subsequently translated into many colour layers, carefully worked over or eroded away using a graphic tablet with the same sensitivity as a brush or finger. In this way each image becomes hand crafted, artistically unique, and solely the product of digital technology.” Examples of images are shown at http://kultur-demo2.eprints.org/399/
Many of Kesseler’s images take up a whole page. After-all this book is not meant to be just a written discourse on fruits but also an expression of the artist Rob Kesseler who has produced many fantastic images of various kinds of fruits. One can easily spend hours reviewing the images and their captions, and many more hours reviewing the text as there is huge amount of information in this book. As a consequence, one will undoubtedly come to realize that fruits are not just something we think of as being edible, but also incredible in the diversity of strange forms, especially if one looks “outside the box” which Stuppy had done well by looking outside the ovarian (pericarp) walls—that in the past, and in the present, botanists have not been able to do when it comes to defining and recognizing the different kinds of fruit.
One may be able to purchase this book below the retail price. For example, Amazona.com has advertised it for $37.80. Moreover, all three books by Kesseler have been available for $113.40 (30 Nov 2008). This is very reasonable. At this price, all public and university libraries should have a least one copy of each.
Richard Spjut, January 2009.
Selected References (Those highlighted are old photocopies in pdf format).
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Acknowledgments to Contributors of Websites
for Photos of Fruit Types
Photos were sought from searches using Google, AltaVista, and Yahoo. Tracing the image to the author(s), however, is not always easy as many sites are not clear in organization, address and purpose.
1. Oregon State University. Department of Horticulture,