Morphological description
Trees , shrubs , scramblers ,lianas , orherbs ; evergreen or deciduous; branches unarmed or armed with stipular thorns (rarely axillary thorns) or scattered prickles on the internodes (Subfamily Mimosoideae; Tribe Caesalpinieae); stems sometimes with buttresses (Koompassia buttress 139533 ). Stipules present, paired, rarely absent, usually caducous; stipels often present in Subfamily Papillionoideae , usually absent in Subfamily Mimosoideae and Subfamily Caesalpinioideae , minute when present there.
Leaves alternate or spirally arranged, pinnate (Subfamily Caesalpinioideae ; Subfamily Papillionoideae ) (Senna alata compl 428845 ), bipinnate (Subfamily Mimosoideae ; Subfamily Caesalpinioideae ) (Acacia farnesiana infl. 431632 ) transformed into phyllodes in Genus Acacia Subgenus Phyllodineae (Acacia mangium phyl 386502 ), or less often, simple, bifoliolate (Genus Bauhinia ) or unifoliolate, extrafloral nectaries on rachis and pinnae present in several genera of Subfamily Mimosoideae and Subfamily Caesalpinioideae (pet gland/pin gland ).
Inflorescences axillary and/or terminal, or cauliflorous, solitary or fascicled, simple or compound, commonly paniculate or racemose; inflorescence units usually consisting of pedunculate glomerules, spikes, umbels or spike-like racemes. Bracts and bracteoles usually present, often caducous.
Flowers actinomorphic (actinomorphic flower ), bilaterally symmetrical or ± zygomorphic, bisexual, unisexual, or rarely neuter, usually 5-merous. Hypanthium (receptacle) usually present in Subfamily Caesalpinioideae . Sepals 5 or 4, free or partly united, usually imbricate ; valvate in Subfamily Mimosoideae . Petals 5, free or united, usually imbricate in Subfamily Caesalpinioideae , papilionaceous in Subfamily Papillionoideae (papilionaceous flower ); valvate in Subfamily Mimosoideae . Stamens 10 or less in Subfamily Caesalpinioideae , 10 in Subfamily Papillionoideae few to 10 or 15 to numerous in Subfamily Mimosoideae , free, united into a tube, or diadelphuous. Anthers basi- or dorsifixed, sometimes with a small, caducous gland at the apex. Ovaries solitary (to several and free in Subfamily Mimosoideae ), superior, 1-celled. Ovules 1 to many, anatropous, parietal, often superposed in 2 rows on either side of the adaxial suture.
Fruit a pod; variously, usually oblong to linear or strap-shaped, laterally compressed, straight or curved, sometimes winged; dehiscent and 2-valved, valves chartaceous, fleshy, coriaceous, thick, or woody; indehiscent and drupaceous or samaroid, sometimes breaking into 1-seeded segments; with or without pulp; glabrous, hairy, or spiny (Aden pavonina pod 392258 ).
Seeds varying in shape, often flattened, mostly ovate-orbicular in outline, often compressed; inserted transversely, obliquely or longitudinally; testa membranous, coriaceous, crustose, or chartaceous, sometimes with a ± peripheral furrow, the pleurogram ; sometimes arillate; hilar groove present or absent; endosperm present or lacking; cotyledons fleshy or foliaceous; radicle straight, slightly oblique or curved, never folded.
Distribution
Cosmopolitan, many cultivated for food, fodder, timber and soil nutrition.
The Leguminosae are divided into three subfamilies:
1a. Flowers zygomorphic or actinomorphic; petals imbricate in bud. Leaves bipinnate, pinnate, digitate, or less often, simple or unifoliolate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1b. Flowers actinomorphic; petals valvate in bud. Leaves bipinnate, or less often pinnate (Genus Inga ), or reduced to phyllodes (Acacia Subgenus Phyllodineae ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subfamily Mimosoideae
2a. Leaves bipinnate or pinnate, rarely simple or unifoliolate. Adaxial petal covered by (margins of) the lateral ones. Seeds without a hilar groove; embryo with a straight to curved radicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subfamily Caesalpinioideae
2b. Leaves pinnate, sometimes digitate, simple or unifoliolate. Adaxial petal (standard) covering (margins of) the lateral ones. Seeds with a hilar groove; embryo with a curved radicle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subfamily Papillionoideae