Papilionaceae Giseke

Scientific Description

Family Sometimes included in Leguminosae. This family description is currently of the broadly defined Leguminosae, including the other legume families Mimosaceae and Caesalpiniaceae which, along with Papilionaceae, are often treated as subfamilies of Leguminosae.

Habit and leaf form. Trees, or shrubs, or herbs, or lianas, or herbaceous climbers; evergreen, or deciduous; resinous, or not resinous. ‘Normal’ plants, or switch-plants; the switch forms often with the principal photosynthesizing function transferred to stems, or phyllodineous. Leaves well developed (usually), or much reduced (not infrequently). The herbs annual, or biennial, or perennial; plants with neither basal nor terminal concentrations of leaves. Self supporting, or epiphytic, or climbing; the climbers stem twiners, or tendril climbers (via stem or leaf tendrils), or scrambling (then sometimes via hooks). The twiners twining clockwise, or twining anticlockwise (in Phaseolus, Wisteria). Helophytic, or mesophytic, or xerophytic. Heterophyllous (e.g. Acacias with bipinnate juvenile and phyllodineous mature foliage), or not heterophyllous. Leaves minute to very large; nearly always alternate, or opposite to whorled (e.g. some Mirbelieae); spiral, or distichous; ‘herbaceous’, or leathery, or membranous, or modified into spines; imbricate, or not imbricate; petiolate to sessile; non-sheathing; gland-dotted, or not gland-dotted; aromatic (rarely, e.g. Cajanus), or without marked odour; edgewise to the stem (commonly when phyllodineous, especially in Australia), or with ‘normal’ orientation; compound (commonly), or simple; pulvinate (in most woody forms), or epulvinate (characteristic of most herbaceous Papilionoideae); when compound,as is usual, unifoliolate, or ternate, or pinnate (commonly, either pari- or imparipinnate), or palmate, or bipinnate (commonly), or bifoliolate (e.g. Bauhinieae). Leaflets stipellate (especially in woody forms), or not stipellate; pulvinate, or epulvinate. Leaf blades dorsiventral, or isobilateral, or centric. Leaves with stipules (nearly always), or without stipules (e.g., some Mirbelieae). Stipules intrapetiolar; adnate to the petiole, or free of the petiole; scaly, or leafy, or spiny, or represented by glands; caducous, or persistent. Leaves without a persistent basal meristem. Stem anatomy. Nodes tri-lacunar, or penta-lacunar. Secondary thickening absent, or developing from a conventional cambial ring, or anomalous; when anomalous, via concentric cambia (e.g. Koompassia, Derris, Mucuna, Wisteria).

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male and functionally female, or hermaphrodite, functionally male, and functionally female. Unisexual flowers present, or absent. Plants hermaphrodite (in most Caesalpinioideae and Papilionoideae), or monoecious, or andromonoecious, or polygamomonoecious. Entomophilous (mostly), or ornithophilous (commonly in southern Australia), or cheiropterophilous (e.g. Mucuna holtoni, where the nectar guide is a petal functioning as a ‘concave mirror’ for ultrasound). Pollination mechanism conspicuously specialized (with passive presenters via modifications of style and/or corolla keel and/or anther filaments, or explosive as in Medicago), or unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’ (usually), or solitary; in panicles, in fascicles, in racemes, in spikes, and in heads. The terminal inflorescence unit cymose, or racemose (— usually said to be racemose, but frequently with flowers in pseudoracemes bearing nodal clusters of obscure constitution, e.g. Phaseoleae). Inflorescences terminal, or axillary, or leaf-opposed (e.g., in some Bossiaeeae); pseudanthial (e.g. Mimosoideae), or not pseudanthial. Flowers minute to large; regular (Mimosoideae), or somewhat irregular to very irregular (Papilionoideae, most Caesalpinioideae); mostly zygomorphic (in Caesalpinioideae and Papilionoideae); resupinate (sometimes, in pendulous inflorescences or in association with bird pollination), or not resupinate. The floral asymmetry involving the perianth and involving the androecium. Flowers papilionaceous (imbricate-descending, with the posterior petal outside and forming a flag (‘standard’), in most Papilionoideae), or ‘pseudo-papilionaceous’ (‘ascending’ with the anterior members outermost, in most Caesalpinioideae), or neither papilionaceous or pseudo-papilionaceous (more or less regular in Mimosoideae and some Caesalpinioideae, the petals reduced in number or lacking in some Swartzieae and Amorphieae); basically 5 merous. Floral receptacle developing a gynophore (this often adnate to the hypanthium in Caesalpinioideae), or with neither androphore nor gynophore; usually more or less cupular. Free hypanthium present, or absent (often more or less replaced by the calyx tube in Papilionoideae, but conventional descriptions rarely inform precisely on this aspect). Perianth with distinct calyx and corolla (mostly), or sepaline (in 26 genera of Caesalpinioideae, some Swartzieae, some Amorphieae, the corolla can be absent); (3–)5, or (6–)10(–11); 1 -whorled, or 2 -whorled (usually); isomerous, or anisomerous. Calyx 5, or (3–)5(–6); 1 -whorled; polysepalous, or partially gamosepalous, or gamosepalous; imbricate, or valvate (and irregularly splitting in Swartzieae); bilabiate, or unequal but not bilabiate, or regular; persistent (usually), or not persistent (e.g., Lamprolobium); accrescent (rarely), or non-accrescent; with the median member anterior. Epicalyx present (occasionally, representing adnate bracteoles), or absent (mostly). Corolla (1–)5; 1 -whorled; appendiculate (petals variously auriculate, etc.), or not appendiculate; polypetalous, or partially gamopetalous (commonly in Papilionoideae), or gamopetalous (in some Mimosoideae, Sympetalandra in the Caesalpinioideae, Trifolium etc. in the Papilionoideae). Papilionoideae commonly with 2 of the petals joined (the two ventral petals connivent to form the ‘keel’ of the typical ‘papilionate’ corolla), or 4 of the petals joined (with the wings adherent to the keel, e.g. Lens, pisum, Vicia). The joined petals of the papilionate corolla anterior. Corolla imbricate (descending in Papilionoideae, usually ascending in Caesalpinioideae), or valvate (Mimosoideae), or with open aestivation (occasionally); white, or yellow, or orange, or red, or pink, or purple, or blue; or some members persistent (e.g. Trifolium), or deciduous. Petals clawed, or sessile. Fertile stamens usually present, or absent (in female flowers). Androecium (1–)9–10, or 10–50 (often ten, but commonly fewer, especially in Caesalpinioideae, and ‘many’ in numerous Mimosoideae, Maniltoa etc.). Androecial sequence determinable, or not determinable. Androecial members free of the perianth (usually), or adnate (to corolla components, in some Caesalpinioideae and Papilionoideae); all equal, or markedly unequal, or all equal to markedly unequal; free of one another (sometimes), or coherent (in a variety of configurations); when cohering, 1 - adelphous, or 2 - adelphous (commonly with the tenth, posterior stamen free of the rest, whose filaments are united into a tube, or 5 + 5); 1 -whorled (usually, even when diplostemonous, but then the antesepalous members often longer), or 2–6 -whorled (in some Mimosoideae). Androecium exclusively of fertile stamens (nearly always in Papilionoideae and Mimosoideae), or including staminodes. Stamens (1–)9–10, or 10–50 (often ‘many’ in Mimosoideae); reduced in number relative to the adjacent perianth (rarely), or isomerous with the perianth, or diplostemonous (commonly, more or less), or triplostemonous to polystemonous (mainly confined to Mimosoideae). Anthers separate from one another, or connivent; dimorphic, or all alike; dorsifixed, or basifixed (in most Cassieae), or dorsifixed and basifixed (alternating, sometimes); versatile (often), or non-versatile; dehiscing via pores, or dehiscing via longitudinal slits; latrorse, or introrse; tetrasporangiate; appendaged (Indigofera), or unappendaged. The anther appendages of Indigofera apical (glandular). Pollen shed in aggregates (often in Mimosoideae, infrequently elsewhere, e.g. Afzelia), or shed as single grains (usually); when aggregated, in tetrads, or in polyads. Fertile gynoecium present, or absent (in male flowers). Gynoecium 1 carpelled (nearly always), or 2–16 carpelled (in a few Mimosoideae from Australia and New Guinea Archidendron and Brazil (Affonsea, Klugiodendron). The pistil 1 celled (nearly always), or 2 celled (by a false septum, e.g. in Mirbelia). Gynoecium partly petaloid (Petalostylis having 3 petaloid style lobes), or non-petaloid. Carpels reduced in number relative to the perianth (mostly), or isomerous with the perianth to increased in number relative to the perianth. Gynoecium monomerous (usually), or apocarpous; of one carpel (usually), or eu-apocarpous (rarely); superior. Carpel apically stigmatic; 2–100 ovuled (i.e. to ‘many’, usually in alternating rows along the placenta). Placentation marginal (along the ventral suture). Gynoecium median (the placenta posterior, on the ventral suture). Ovary sessile to stipitate. Ovules pendulous to ascending; biseriate; arillate, or non-arillate; anatropous, or campylotropous to amphitropous, or hemianatropous.

Fruit and seed features. Fruit subterranean (Arachis), or aerial; non-fleshy, or fleshy; hairy, or not hairy; an aggregate (rarely, in Mimosoideae), or not an aggregate. The fruiting carpel dehiscent, or indehiscent; a legume (usually), or a follicle, or an achene, or samaroid, or a loment, or drupaceous. Pods transversely septate between the seeds, or not transversely septate. Valves of the dehisced pod twisted, or not twisted. Fruit elastically dehiscent, or passively dehiscent. Dispersal unit the seed, or the fruit. Seeds commonly non-endospermic, or endospermic (then often scantily so); small to very large; winged (e.g. some Mimosoideae), or wingless; with starch, or without starch; with amyloid, or without amyloid. Cotyledons 2; when radicle flexed, accumbent. Embryo chlorophyllous (45/83 — representing all three subfamilies); straight to bent (the radicle straight in Mimosoideae and most Caesalpinioideae, but oblique in a few Caesalpinioideae, usually inflexed but occasionally short and straight in Papilionoideae). Micropyle zigzag, or not zigzag. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Nitrogen-fixing root nodules present (very commonly), or absent (seemingly of rare occurrence in Caesalpinioideae). Aluminium accumulation not found. Photosynthetic pathway: C₃.

Geography, cytology, number of species. Holarctic, Paleotropical, Neotropical, Cape, Australian, and Antarctic. World distribution: cosmopolitan. 12000 species.

Economic uses, etc. Economically very important for food, fodder, fibres, dyes, gums, resins, oils, and ‘green manure’; e.g. peas (Pisum), lentils (Lens), peanuts (Arachis), beans (Phaseolus, Vicia), cowpeas (Vigna), soybean (Glycine), clover (Trifolium), alfalfa (lucerne, Medicago), lupins (Lupinus), sweet clover (Melilotus). Numerous cultivated ornamentals, e.g. Bauhinia, Wisteria, Acacia, Cassia, Cytissus, Genista, Albizia, Lathyrus. Important tropical timbers from Acacia, Albizzia, Dalbergia, Robinia, Sophora, etc.

Additional comments. Clearly, the many features which tend to distinguish the subfamilies all either involve rather numerous exceptions, are (or seem likely to be) very incompletely documented, or are not universally applicable.