A Systematic Treatment of Fruit Types

©The World Botanical Associates Web Page
Prepared by Richard W. Spjut
April 2003, March 2004; Feb. 2006; March 2007; Sep 2007, Jan 2008

     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
     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
     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) 
     Selected References (old photocopies in pdf format of historical references)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.

Available from the New York Botanical Garden: Mem. New York Bot. Gard., Vol 70, 181 pp, 53 plates, 153 illus. 1994.

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.

Classification of Fruit Types

Note: Text highlighted are links to photos at other websites, which are
referenced by number to citations below, some of which are bookmarked.
Additionally, many photos below also appear directly linked to this website.
These are reproduced with permission as noted, and are considered copyrighted
by the person or organization as acknowledged.  For any reproduction or use.
of any photo  you should contact the website or person directly.
 

A. Spermatocarpia (“naked seeds”)

     Spermidium. Seed lacking bracts or scales, integuments drupaceous, the outer fleshy, inner
           hardened (Gingoaceae
1).
     Arillocarpium. Seed with aril-like covering (Cephalotaxaceae,
2, Gnetaceae,4 Taxaceae).
     Epispermatium.  Seed on a swollen or receptacle stalk (Podocarpaceae
3)
     Arcesthida. Seeds covered by fleshy bracts or scales (Cupressaceae [Juniperus
5], Ephedraceae [Ephedra]).
     Galbulus.  Scale and seed bract fused. (Araucariaceae
6, Cupressaceae (Platycladus),7 Taxodiaceae8).
     Strobilus.  Seeds on frondlike sporophylls loosely aggregate at ends of shoots (Cycadaceae
9).
     Simple Cone. Seeds on scale-like sporophylls in a cylindrical arrangement (cone).
           (Stangeriaceae,
11 Zamiaceae12).
     Compound Cone.  Seed scales subtended by a distinct bract (Pinaceae,
13 Welwitschiaceae14).
 

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 (Anthocarp).

Dehiscent

               Tryma. Anthocarp dehiscent (Arecaceae [Astrocaryum munbaca], Juglandaceae [Carya15],
                    Thymelaeaceae [Thymelaea velutina]).

Indehiscent

Aril-like

               Glans.  Pericarpium subtended (basally) by accrescent floral parts (receptacle, peduncle, pedicel,
                    bracts, or sepals) (17+ families: Anacardiaceae [Anacardium
16], Fagaceae [Quercus garryana17a
                    Quercus macrocarpa/Q. lyrata
17b], Lauraceae [Aniba, Licaria, Ocotea18],
                   
Urticaceae [Laportea]).

Not aril-like

Dry

               Pseudoanthecium. Anthocarp of the Cyperaceae, the pericarpium in a sac-like structure (Carex19).
               Pseudosamara.  Anthocarp winged at one end (17+ families: Cunoniaceae [Aphanopetalum],
                    Diptercarpaceae,
20 Hernandiaceae [Gyrocarpus], Juglandaceae [Engelhardia], Ochnaceae
                    [Lophira]).
               Diclesium. Anthocarp of floral parts, which may be winged, ribbed, or spiny
                    (29+ families: Betulaceae [Corylus
21], Combretaceae,22 Nyctaginaceae,23 Polygonaceae,
                    Solanceae [Physalis
24]).
               Cypsela. Anthocarp with bristles or paleae (Anacardiaceae [Cotinus], Asteraceae [Microseris
25],
                    Cyperaceae [Scirpus
26a]).

Fleshy

               Acrosarcum. Seeds embedded in fleshy pulp without distinct endocarp Basellaceae [Basella],
                     Cactaceae [Opuntia
26b], Elaeagnaceae [Shepherdia], Lauraceae [Cryptocarya]
               Balausta
.  Anthocarp with seeds having a swollen testa (Punicaceae
27).
               Pome. Anthocarp with an endocarpic pericarpium (Idiospermaceae, Olacaceae [Onkogea
28],
                     Rhamnaceae [Paliurus], Rosaceae [Malus
29]).
               Pseudodrupe. Anthocarp differentiated only by the pericarpium, which lacks an endocarp
                     [Elaeagnaceae (Elaeagnus
30), Myricaceae (Myrica), Juglandaceae (Juglans31), Lauraceae
                     (Cryptocarya), Moraceae (Pseudolmedia
32), Myricaceae (Myrica33)].

          Gymnocarpi.  Pericarpium developing without accessory floral parts, from one flower.

               Lomentaceous FruitsPericarpium transversely constricted into seed bearing segments,
                    disarticulating at the constrictions.

                    Lomentum. Pericarpium of one carpel with complete disarticulation (Fabaceae [Desmodium34a]).
                    Craspedium.  Pericarpium not completely disarticulating, replum persistent
                         (Mimosaceae [Mimosa
34b]).
                    Bilomentum.  Pericarpium of more than one carpel and disarticulating (Brassicaceae [Raphanus
34c],
                         Capparaceae [Maerua
35], Fumariaceae [Hypecoum], Goodeniaceae [Lechenaultia]).

               Drupaceous Fruits.  Pericarpium internally differentiated by an endocarp, which may be of one or
                    more stones.

                    Drupe.  Pericarpium mostly fleshy except for endocarp (76+ families: Anacardiaceae [Mangifera36a
                         Rhus
36b], Cornaceae [Cornus], Oleaceae [Olea europaea], Rhamnaceae [Rhamnus], Rosaceae
                         [Prunus persica
37]).
                    Nuculanium. Pericarpium partly or entirely dry, sometimes splitting (20+ families: Arecaceae
                         [Cocos nucifera
38], Chrysobalanaceae [Licania39], Loganiaceae [Neuburgia], Rosaceae
                         [Prunus amygdalus
40], Zygophyllaceae [Balanites]).

               Simple Dry Fruits.  Pericarpium not differentiated by endocarp, dry.

                    Samara.  Pericarp extended into a wing, longer than the seed (14+ families: Caesalpiniaceae
                         [Pterocarpus
41], Oleaceae [Fraxinus42], Polygalaceae [Securidaca43], Rhamnaceae [Ventilago],
                         Ulmaceae [Ulmus
44]).
                    Utricle. Pericarpium inflated, easily crushed (8+ families: (Amaranthaceae [Amaranthus viridis],
                         Brassicaceae [Lesquerella], Capparaceae [Isomeris
45], Lemnaceae,46 Passifloraceae [Barteria]).
                    Carcerulus.  Pericarp of more than one carpel, thick, not easily crushed, nut-like
                         (23+ families: Huaceae [Afrostyrax], Lythraceae [Lawsonia], Onagraceae [Circaea
47b,
                         Pedaliaceae [Uncarina
47b], Sphaerocepalaceae [Rhopalocarpus], Sterculiaceae [Apeiba]).
                    Camara. Pericarpium of one carpel, coriaceous, slightly fleshy or dry, seeds free (9+ families:
                         Degeneriacae, Fabaceae [Medicago
48], Krameriaceae, Posidoniaceae, Sapindaceae [Litchi49]).
                    Achene.  Pericarp adhering closely to seed(s), distinct from testa, cotyledons usually 2
                         (12+ families: Asteraceae [Helianthus
50a], Brassicaceae [Calepina], Najadaceae).
                    Caryopsis. Pericarp very thin, hyaline and often indistinct from testa, cotyledons 1,
                         rarely occurring as fruit (Poaceae [Eragrostis starosselskyi, Sorghum bicolor
50b.Triticum50c].

               Simple Fleshy Fruits. Pericarpium not differentiated by endocarp, fleshy.

                    Bacca.  Pericarpium with a thin outer skin-like layer, collapsing when removed
                         from sarcocarp (53+ families: Berberidaceae [Podophyllum
51], Chenopodiaceae [Rhagodia52],
                         Ericaceae [Vaccinium
53], Lauraceae [Persea54], Solanaceae [Lycium55]).
                    Amphisarcum. Pericarpium with a dry outer crust, firm (15+ families: Bignoniaceae
                         [Crescentia
56], Bombacaceae [Adansonia57], Cucurbitaceae [Lagenaria58], Lecythidaceae
                         [Gustavia
59], Theaceae).
                    Hesperidium.  Pericarpium with a coriaceous outer layer (rind) and with septa, usually
                         derived from axile placentation (Nymphaeaceae [Nymphaea], Rutaceae [Citrus
60]).
                    Pepo.  Pericarpium with a coriaceous outer layer and without septa, usually derived from parietal
                          or apical placentation.
                         (Caricaceae,
61 Cucurbitaceae [Cucurbita62], Musaceae [Musa sapientum63], Passifloraceae64).

     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],
               Proteaceae [Grevillea
65]).
          Coccum. Opening along two sutures (unequal in length, often woody), fruit not of the Fabales, but
               often of the Connaraceae,
Myristicaceae,66 and Proteaceae.67
          Legume.  Opening along two sutures (often of equal length, nonligneous), fruit of the Fabales.
68

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
                         suffruticosa
69a), Gentianaceae [Gentiana], Liliaceae [Burchardia], Zygophyllaceae
                         [Guaiacum
69b]).
                    Loculicidal Capsule. Opening along dorsal suture (86+ families: Acanthaceae [Carlowrightia],
                         Celastraceae [Maytenus], Liliaceae (Lilium
70), Lythraceae (Lagerstroemia),
                         Meliaceae
[Trichilia], Rubiaceae [Crossopteryx]).                   

               Incomplete Dehiscence: Opening <20%  along sutures, or with persistent replum or columella, or
                         with other persistent inner capsular (placental or endocarp) parts.

                    Denticidal Capsule. Opening only part way, < 20% of suture length (Caryophyllaceae
                          [Cerastium
71], Dioscoreaceae [Dioscorea], Lythraceae [Lythrum], Menyanthaceae,
                          Primulaceae [Dodecatheon
72a], Ranunculaceae [Nigella72b]).
                   
Septifragal Capsule.  With columella (columnar or narrow central partition, 15+ families:
                         Convolvulaceae [Ipomoea], Ericaceae [Rhododendron
73a], Meliaceae [Toona73b],
                         Polemoniaceae [Collomia], Stylidiaceae).
                    Polospermatium.  Capsule with persistent columella that has seeds attached
                         (Euphorbiaceae [Austrobuxus, Spondianthus, Hugoniaceae [Ctenolophon].
                    Siliqua (includes silicle).  Capsule with parietal seeds attached to a replum that
                         has a partition (Brassicaceae
74).
                    Ceratium.  Capsule with seeds attached to an axile partition, or if seeds parietal then
                         without partition (20+ families: Aristolochiaceae [Aristolochia
75], Bignoniaceae,
                         Capparaceae [Cleome], Fumariaceae [Corydalis], Papaveraceae [Papaver
76]).

          Irregular Capsules: Localized sutures or pores, or breaking apart along cracks, or rupturing from
               accrescent seeds.

               Pyxidium. Capsule opening by a lid, or a common pore, that encircles all carpels (17+ families:
                    Amaranthaceae [Amaranthus caudatus
77], Berberidaceae [Jeffersonia], Cucurbitaceae
                    [Ecballium
78a, Luffa78b], Lecythidaceae [Lecythis79], Myrtaceae [Eucalyptus80],
                    Plantaginaceae [Plantago
81]).
               Poricidal Capsule. Opening by one or more localized pores on each carpel (Campanulaceae
                    [Triodanis
82], Loganiaceae [Mitreola], Saxifragaceae [Penthorum83], Scrophulariaceae [Kickxia]).
               Fissuricidal Capsule. Opening by one longitudinal (linear) slit, or by many linear parallel slits
                    (19+ families: Hydrostachyaceae, Lentibulariaceae [Utricularia], Orchidaceae,
84 Oxalidaceae,85
                    Staphyleaceae)
               Foraminicidal Capsule. Opening by cracks that spread in different directions (12+ families:
                    Araceae [Alocasia], Burmanniaceae [Dictyostega], Cuscutaceae, Garryaceae, Lythraceae
                    [Ammannia]).
               Glandispermidium. Capsule breaking apart from accrescent seeds (Berberidaceae [Caulophyllum
86],
                    Liliaceae [Ophiopogon,
87 Violaceae [Gymnorinorea]).

     III. Schizocarpic Fruits.  Fruitlets derived from a compound pistil separating into its carpellary
                                                   constituents.

With accessory parts

                    Glandarium.  Receptacle accrescent (Ochnaceae [Ochna,88 Ouratea]).
                    Diclesarium.  Fruitlets developing within an accrescent perianth (Lamiaceae [Salazaria]).
                    Trymarium.  Perianth splitting to disperse fruitlets (Lamiaceae [Aeollanthus, Icomum]).

Without accessory parts

Dry

                    Coccarium.  Monocarps (fruitlets) opening along two sutures (23+ families: Euphorbiaceae,89
                          Hamamelidaceae, Liliaceae [Acanthocarpus], Rutaceae [Zanthoxylum], Sterculiaceae
                          [Helicteres]).
                    Follicarium.  Monocarps opening along one (ventral) suture (Apocynaceae,
90 Asclepiadaceae,91
                          Cunoniaceae [Spiraeanthemum], Hippocrateaceae [Reissantia], Petrosaviaceae,
                          Sterculiaceae [Sterculia
92]).
                    Microbasarium.  Fruitlets separating along septa of bilobed (two-locular) carpels, each
                          fruitlet a half-carpel (mericarp) (Callitrichaceae,
93 Convolvulaceae [Falckia], Lamiales94).
                    Lomentarium.  Fruitlets disarticulating between constricted seed segments
                          (Apocynaceae [Alyxia
95], Papaveraceae [Platystemon])
                    Polachenarium.  Monocarps separating from a longitudinal central axis (columella,
                           or carpophore), dehiscent or indehiscent, often remaining attached to axis at
                           maturity (9+ families: Apiaceae,
96 Geraniaceae [Erodium97a, Geranium97b],
                          
Juncaginaceae [Triglochin], Malpighiaceae, Banisteriopsis], Rubiaceae [Anthospermum]).
                    Samarium.  Monocarps with wings longer than seeds (7+ families: Aceraceae,
98 Malpighiaceae,99
                           Sapindaceae [Atalaya], Simaroubaceae [Ailanthus
100], Trigoniaceae [Trigoniastrum]). 
                    Camarium.  Monocarps with seeds free from pericarp, indehiscent or tardily dehiscent
                           (Gyrostemonaceae [Gyrostemon], Malvaceae [Malva
101], Sapindaceae [Alectyron],
                           Zygophyllaceae [Tribulus
102]).
                    Achenarium.  Monocarps indehiscent with pericarp contiguous to seed (15+ families:
                           Globulariaceae, Haloragaceae (Myriophyllum), Limnanthaceae, Nolanaceae,
                           Sphaerosepalaceae [Dialyceras]).

Fleshy

                    Baccarium.  Endocarp indistinct (Apocynaceae [Hunteria], Oleaceae [Jasminum],
                           Phytolaccaceae [Phytolacca
103], Saururaceae [Saururus], Tropaeolaceae [Tropaeolum]).
                    Druparium.  Endocarp evident (Cneoraceae, Malvaceae [Malvaviscus], Ochnaceae
                           [Brackenridgea], Simaroubaceae [Holacantha
104], Tiliaceae [Grewia]).

 

     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)
                    Diclesetum. Fruitlets covered by perianth (Cabombaceae [Cabomba], Coriariaceae
106),
                          Dilleniaceae (Dillenia indica).
                    Pomarium.  Fruiting receptacle divided into many cavities (Lauraceae [Ravensara],
                         Monimiaceae [Siparuna], Nelumbonaceae
107).
                    Pometum.  Fruiting receptacle or hypanthium with one cavity (Calycanthaceae,
108
                         Eupomatiaceae, Monimiaceae [Glossocalyx], Rosaceae [Agrimonia, Cotoneaster, Rosa
109]).
                    Glandetum. Fruiting receptacle accrescent (Rosaceae [Duchesnea,
110a Fragaria110b],
                          Sargentodoxaceae).
                    Syncarpium. Fruitlets (apocarps) concrescent (Annonaceae [Annona
111], Himantandraceae
                         [Galbulimima
112], Magnoliaceae [Magnolia ashtonii], Winteraceae).

               Etairionari.  Multiple fruitlets without accessory (floral) parts.

Dehiscent

                    Follicetum.  Carpels (apocarps) opening along one suture (21+ families, e.g., Crossosomataceae113
                         Paeoniaceae,
114a Magnolia (Magnoliaceae), Ranunculaceae [Delphinium]),
                         Trochodendraceae [Trochodendron
114b].
                    Coccetum.  Carpels (apocarps) opening along two sutures (Dilleniaceae [Tetracera
115],
                         Magnoliaceae [Michelia], Rosaceae [Vauquelinia]).

Indehiscent

Dry

                    Samaretum.  Apocarps winged (Eupeteleaceae, Magnoliaceae [Liriodendron116]).
                    Achenetum.  Apocarps one seeded, pericarp contiguous (7+ families: Alismataceae [Alisma
117],
                         Cabombaceae [Brasenia], Circaeasteraceae, Ranunculaceae [Clematis
118a, Ranunculus118b]).
                    Camaretum.  Apocarps more than one seeded, pericarp free (Alismataceae [Damasonium],
                         Annonaceae [Uvaria
119a], Dilleniaceae [Curatella], Lardizabalaceae [Decaisnea119b]).
                    Lomentetum.  Apocarps constricted between seeds (Annonaceae [Monanothotaxis
120]).

Fleshy

                    Drupetum.  Seeds enclosed by a firm endocarp (Amborellaceae,
                          Menispermaceae [Coscinum], Rosaceae [Rubus
121], Ruppiaceae}).
                    Baccetum. Seeds in an undifferentiated sarcocarp (Annonaceae [Asimina
122]),
                          Austrobaileyaceae, Lardizabalaceae [Boquila], Ranunculaceae [Hydrastis
123],
                          Schisandraceae,
124 Winteraceae [Belliolum]).

     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].
               Catoclesium.  Fruitlets covered by leaves, bracts or perianth (Apiaceae [Anisociadium],
                     Asteraceae [Xanthium
126], Calyceraceae [Acicarpha, Chenopodiaceae [Beta], Poaceae
                     [Coix, Zea]).
               Trymosum.  Fruitlets dispersed by opening of the receptacle or bracts (Fagaceae
                     [Castanea
127], Moraceae [Dorstenia]).
               Trymoconum.  Fruitlets in dehiscent cone-like structures, each fruitlet dispersed by dehiscent
                     bracts (Casuarinaceae,
128 Cyclanthaceae).
               Achenoconum. Fruitlets in indehiscent cone-like structures, scales sometimes deciduous
                     (Betulaceae,
129 Cannabaceae [Humulus], Grubbiaceae, Proteaceae [Isopogon, Petrophile]).

          Phenocarpi. Fruitlets mostly exposed, which may include an accrescent perianth.

Dehiscent

               Folliconum.  Fruitlet of one carpel (Proteaceae [Banksia130]).
               Capsiconum. Fruitlet of more than one carpel (Cunoniaceae [Pancheria], Hamamelidaceae
                      [Liquidambar
131], Myrtaceae [Conothamnus], Salicaceae, Saururaceae [Anemopsis]).

Indehiscent

               Glandosum.  Fruitlets on a swollen base (peduncle or receptacle, Urticaceae [Procris].
               Bibacca.  Of two partially fused fruitlets (Caprifoliaceae [Lonicera
132], Chenopodiaceae [Didymanthus],
                    Rubiaceae [Mitchella
133]).
               Achenosum.  Of more than two dry fruitlets (Platanaceae [Platanus
134], Rubiaceae [Breonia135],
                   Sparganiaceae
136, Urticaceae [Leucosyke]).
               Sorosus. Of more than two fleshy fruitlets (13+ families: Bromeliaceae [Ananas
137], Cyclanthaceae
                   [Carludovica], Moraceae [Morus
138], Pandanaceae, Rubiaceae [Morinda citrifolia]139).

          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
                    (Many genera: e.g., Agrostis,
140 Calamgrostis, Milium, Oryzopsis, Zizania).
               Anthecetum. Fruit derived from a spikelet with glumes, or with more than one floret, disarticulation
                     below or above glumes (Alopecurus,
141 Arrhenatherum,142 Chloris, Ctenium, most Paniceae, and
                     other taxa).
               Anthecarium.
143  Disarticulation occurring in multiple places along a rachilla (most grasses
                     except Paniceae).
               Anthecosum. Concrescent spikelets (Anthephora, Buchlo
ë,144 Cenchrus,145 Tragus).
               Follicular Anthecetum. With a dehiscent pericarpium (Centrolepidacae [Centrolepis], Hydatellaceae
                     [Trithuria], Poaceae [Eleusine]).
               Racharium.  Pericarpium embedded in a rachis that breaks apart at maturity (Agropyron
146, Hordeum,
                     Monerma, Parapholis, Stenotaphrum).
               Infructum.  Inflorescence breaking apart at base (Aegilops
147, Apluda, Chamaeraphis, Schedonnardus).
               Infructarium. Inflorescence breaking up along multiple parts of the plant (Munroa).
               Pseudosamarosum. New term suggested for the fruit of Tilia
148

            
 
How  Fruits are Classified

             
Pericarpium and Anthocarp:
Their Classification According to Gynoecial Structures

 

     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
           together in fruit.

     (2) Syncarpous—of carpels united at their margins (compound pistil) that remain united in fruit,
           except for dispersal of seed via sutural dehiscence (includes coenocarpous, lysicarpous, and
           paracarpous of Levina, 1961 and Parkin, 1955; eusyncarpous of Winkler, 1940).

     (3) Schizocarpous—of united or partially united carpels that separate from each other into distinct
           seed- containing units in fruit (includes dyssyncarpous of Winkler, 1940).

     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.
(2) Follicle—dehiscent along one suture and unicarpellate.
(3) Coccum—dehiscent along two sutures and unicarpellate.
(4) Achene—indehiscent, one-seeded with the pericarp contiguous with the seed.
(5) Carcerulus—composed of more than one carpel, dry and indehiscent or irregulary dehiscent, without differentiation of an endocarp, the pericarp free from the testa.
(6) Bacca—indehiscent and internally fleshy.
(7) Drupe—one or more seeds enclosed in an internal stone.
(8) Capsule—dehiscent and composed of more than one carpel.
(9) Samara—pericarp contiguous with the seed and extending into one or more wings exceeding the length of the seed.
(10) Loment—disarticulating between seeds.

     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—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.


What is an anthocarp?
   A pericarpium with attached floral parts that have undergone a marked development during post-fertilization to aid in the dissemination of the seed(s).

Six basic types of anthocarps are recognized:

(1) Glans—receptacle or pedicel or peduncle enlarged
(2) Diclesium—calyx or hypanthium enlarged, indehiscent and dry
(3) Pome—calyx or hypanthium enlarged, indehiscent and fleshy
(4) Tryma—active calyx or hypanthium
(5) Cypsela--hypanthium or calyx developing primarily into terminal wings or bristles
(6) Anthecium—single fertile-floreted spikelet, disarticulating above the glumes

     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).

 

The Need for Standardized Meanings to Fruit Terms
An Historical Perspective

      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, although 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). 

     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, for a total of 35 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.  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 should have made reference 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 other 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.

      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.