©The
World Botanical Associates Web Page
Prepared by Richard W. Spjut
April 2003, March 2004; Feb. 2006; March 2007; Sep 2007, Jan 2008, March 2009
Abstract
Supporting References
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format of historical references)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
|
Abstract 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.
Supporting References. 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
of pericarpium Dehiscent
Tryma. Anthocarp dehiscent (Arecaceae [Astrocaryum munbaca],
Juglandaceae [Carya15], Indehiscent Aril-like
Glans. Pericarpium subtended (basally) by accrescent floral
parts (receptacle, peduncle, Not aril-like Dry
Pseudoanthecium. Anthocarp of the Cyperaceae, the pericarpium in a
sac-like Fleshy
Acrosarcum.
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
(Fabaceae [Desmodium34a]).
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,
Connaraceae [Cnestidium], 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
(Caryophyllaceae
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
(17+ families: III. Schizocarpic Fruits. Fruitlets derived from a compound pistil separating into its carpellary With accessory parts
Glandarium. Receptacle accrescent (Ochnaceae [Ochna,88
Ouratea]). Without accessory parts Dry
Coccarium. Monocarps (fruitlets) opening along two sutures
(23+ families: Euphorbiaceae,89c Fleshy
Baccarium. Endocarp indistinct (Apocynaceae [Hunteria],
Oleaceae [Jasminum],
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. Dehiscent
Follicetum. Carpels (apocarps) opening along one suture (21+
families, e.g.,
Crossosomataceae113 Indehiscent Dry
Samaretum. Apocarps winged (Eupeteleaceae, Magnoliaceae [Liriodendron116]). Fleshy
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
[Ficus,125 Naucleopsis]. Phenocarpi. Fruitlets mostly exposed, which may include an accrescent perianth. Dehiscent
Folliconum. Fruitlet of one carpel (Proteaceae [Banksia130]). Indehiscent
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,
Although 95
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
of a
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: (1)
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.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Basic Types of Pericarpia According to Gynoecial Structures
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: (1)
Glans—receptacle or pedicel or
peduncle enlarged The first four terms are employed in the different classes of gynoecial structures; these are exemplified as follows:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Basic Types of Anthocarps According to Gynoecial Structures
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
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.
(1)
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.
|
