General Characters Of Fabaceae

General Characters Of Fabaceae

The Fabaceae are mostly herbs but include also shrubs and trees found in both temperate and tropical areas. They comprise one of the largest families of flowering plants, numbering some 400 genera and 10,000 species. The leaves are stipulate, nearly always alternate, and range from pinnately or palmately compound to simple. Like the other legume families the petiole base is commonly enlarged into a pulvinus. The flowers are slightly to strongly perigynous, zygomorphic, and commonly in racemes, spikes, or heads. The perianth commonly consists of a calyx and corolla of 5 segments each. The petals are overlapping (imbricate) in bud with the posterior petal (called the banner or flag) outermost (i.e., exterior) in position. The petals are basically distinct except for variable connation of the two lowermost ones called the keel petals. The lateral petals are often called the wings. The androecium most commonly consists of 10 stamens in two groups (i.e., they are diadelphous with 9 stamens in one bundle and the 10th stamen more or less distinct). The pistil is simple, comprising a single style and stigma, and a superior ovary with one locule containing 2-many marginal ovules. The fruit is usually a legume.


Leguminosae-Papilionoideae DC.
Alternatively Fabaceae Lindl. (ambiguous nom altern.), Papilionaceae Giseke
~ Leguminosae
Including Hedysareae (Hedysaraceae) J.G Agardh, Lathyraceae Burnett, Lotaceae Burnett, Phaseolaceae Ponce de Léon & Alvares, Robiniaceas (Robiniaceae) Welw., Swartzieae (Swartziaceae) Bartl.

Habit and leaf form. Trees, or shrubs, or herbs, or lianas; 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; with neither basal nor terminal aggregations 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, or not heterophyllous. Leaves evergreen, or deciduous; minute to very large; alternate (usually), or opposite to whorled (e.g. some Mirbelieae); spiral, or distichous; ‘herbaceous’, or leathery, or membranous, or modified into spines; petiolate to sessile; non-sheathing; gland-dotted, or not gland-dotted; aromatic (occasionally, e.g. Cajanus), or without marked odour (mostly); edgewise to the stem (commonly when phyllodineous, especially in Australia), or with ‘normal’ orientation; compound (commonly), or simple (or only ostensibly so); pulvinate, or epulvinate (the distinction being indicative of a major taxonomic distinction); when compound, as is usual, unifoliolate, or ternate, or pinnate (commonly, either pari- or imparipinnate), or palmate, or bifoliolate. Leaflets pulvinate, or epulvinate. Leaves stipulate (nearly always), or exstipulate (e.g., switch plants and some non-switch Mirbelieae). Stipules intrapetiolar; free of one another, or concrescent (or more often adnate to the petiole); scaly, or leafy, or spiny, or represented by glands; caducous, or persistent. Leaves without a persistent basal meristem.

Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata anomocytic, or paracytic, or anisocytic, or tetracytic, or cyclocytic. Urticating hairs absent (but present on calyces and pods of Mucuna).
Lamina dorsiventral, or isobilateral, or centric; with secretory cavities, or without secretory cavities. Secretory cavities containing oil, or containing mucilage, or containing resin. The mesophyll containing mucilage cells, or not containing mucilage cells; with sclerencymatous idioblasts (occasionally?), or without sclerenchymatous idioblasts. Minor leaf veins with phloem transfer cells, or without phloem transfer cells (Watson and Gunning 1981).

Stem anatomy. Secretory cavities present, or absent. Cork cambium present (usually), or absent; initially deep-seated, or superficial. Nodes tri-lacunar, or penta-lacunar. Primary vascular tissue in a cylinder, without separate bundles, or comprising a ring of bundles. Cortical bundles present, or absent. Medullary bundles absent. Internal phloem absent. Secondary thickening absent, or developing from a conventional cambial ring, or anomalous; when anomalous, via concentric cambia (e.g. Derris, Mucuna, Wisteria). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones, or not stratified. ‘Included’ phloem present, or absent. Xylem with vessels. Vessel end-walls simple. Vessels with vestured pits (commonly), or without vestured pits. Wood storied, or partially storied (VPI); parenchyma apotracheal, or paratracheal. Sieve-tube plastids P-type (93 genera), or S-type (13 genera); when P-type type IV (seemingly always subtype (b)).

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite (mostly). Entomophilous, or ornithophilous (especially common 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 at least two forms of passive presenter, involving modifications of the style and/or of the keel of the corolla and/or the staminal filaments, and explosive pollination in (e.g.) Medicago), or unspecialized.

Inflorescence, floral, fruit and seed morphology. 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 (— often ostensibly racemose, but frequently paniculate or, as in Phaseoleae, having pseudoracemes bearing nodal clusters of obscure constitution). Inflorescences terminal, or axillary, or leaf-opposed (e.g., in some Bossiaeeae). Flowers minute to large; calyptrate (rarely), or not calyptrate; somewhat irregular to very irregular (mostly), or regular (some Sophoreae and Swartzieae); usually zygomorphic; resupinate (sometimes, in association with bird pollination or in pendulous inflorescences), or not resupinate. The floral irregularity involving the perianth and involving the androecium.
Flowers papilionaceous (usually, with the corolla imbricate-descending, the posterior petal raised to form a flag (‘standard’), and the lower petals housing the stamens and gynoecium), or neither papilionaceous nor pseudo-papilionaceous (occasionally, in Sophoreae, Swartzieae, Amorphieae); tricyclic, or tetracyclic (usually). Floral receptacle developing a gynophore, or with neither androphore nor gynophore; usually more or less cupular. Free hypanthium present (e.g. commonly in Dalbergieae), or absent.
Perianth with distinct calyx and corolla (usually), or sepaline (corolla sometimes missing in Swartzieae, Amorphieae); (5–)10(–11) (?); 2 whorled; isomerous, or anisomerous. Calyx 5, or (3–)5(–6) (?); 1 whorled; usually gamosepalous (below); unequal but not bilabiate, or bilabiate, or regular; persistent (usually), or not persistent (e.g., Lamprolobium); accrescent (rarely), or non-accrescent; ascending imbricate; when pentamerous, with the median member anterior. Epicalyx present (representing adnate bracteoles, e.g. in Pultenaea), or absent. Corolla when present, 5 (usually), or 1–5 (Amorphieae, Swartzieae); 1 whorled; appendiculate (petals often auriculate, etc.), or not appendiculate; polypetalous, or partially gamopetalous, or gamopetalous (rarely, e.g. in Trifolium, where sometimes all the petals are adnate to the androecial tube). Commonly with 2 of the petals joined (the two ventral petals commonly connivent to form the ‘keel’ of the typical ‘papilionate’ corolla), or 4 of the petals joined (with the wings adnate to the keel, e.g. Lens, Pisum, Vicia). The joined petals anterior (or anterior and lateral). Corolla imbricate (descending, with the adaxial member outside and forming a flag (‘standard’)); 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.
Androecium (5–)9–10(–30) (to ‘many’ only in a few Swartzieae and Sophoreae). Androecial members free of the perianth (mostly), or adnate (e.g. in Dalbergieae, Mirbelieae, Trifolium, Genista, etc., where at least some members or the androecial tube can be attached to corolla components); all equal, or 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); even when 10, 1 whorled (though the antesepalous, theoretically ‘outer’ members develop first, are often longer, and their anthers may differ from those of the antepetalous members). Androecium exclusively of fertile stamens (seemingly with very few exceptions — e.g. Robynsiophyton in the Crotalarieae). Stamens (5–)9–10(–30); isomerous with the perianth (rarely), or diplostemonous (commonly, more or less), or triplostemonous to polystemonous (rarely). Anthers separate from one another to connivent; dorsifixed, or basifixed, or dorsifixed and basifixed (alternating); versatile, or non-versatile; dehiscing via longitudinal slits; introrse, or latrorse; bilocular (usually), or unilocular to bilocular (the thecae sometimes confluent above); tetrasporangiate; appendaged (e.g. gland-tipped in Indigofera), or unappendaged. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer; of the ‘dicot’ type. Tapetum usually glandular. Pollen shed as single grains. Pollen grains aperturate (usually), or nonaperturate; (2–)3(–4) aperturate, or 6 aperturate; colporate (commonly), or porate, or colpate, or rugate; 2-celled.
Gynoecium 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled (nearly always), or 2 celled (by a false septum, e.g. Mirbelia). Gynoecium monomerous; of one carpel; superior. Carpel apically stigmatic; (1–)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; bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked (often with filiform apparatus). Endosperm formation nuclear. Endosperm haustoria present; chalazal, or lateral (rarely). Embryogeny onagrad, or asterad, or caryophyllad.
Fruit non-fleshy, or fleshy. The fruiting carpel dehiscent, or indehiscent; a legume (usually), or a follicle, or an achene, or samaroid, or a loment, or drupaceous. Fruit elastically dehiscent, or passively dehiscent. Dispersal unit the seed, or the fruit. Fruit (1–)2–100 seeded (to ‘many’). Seeds thinly endospermic, or non-endospermic; small to very large; wingless (always?). Seeds with starch, or without starch. Seeds without amyloid. Cotyledons 2; usually flat. Embryo chlorophyllous; nearly always bent (the radicle nearly always inflexed, but rarely short and straight). Micropyle zigzag, or not zigzag.