Morfological description
Trees , shrubs , scramblers , lianas , or herbs with a more of less woody base; evergreen or deciduous; sometimes armed with thorns or spines (Tribe Caesalpinieae ; Caes cucullata thorns 139589 ); buttresses sometimes present.
Leaves usually spirally arranged, bipinnate, pinnate, or unifoliolate, petiolate. Leaflets rarely reduced and rachis phyllodial, rarely with pellucid dots. Extrafloral nectaries present in several genera. Stipules nearly always present, paired, often caducous; stipels usually lacking, minute when present.
Inflorescences axillary and/or terminal, or cauliflorous (cauliflora Cynom infl 386534 ), solitary or fascicled, commonly paniculate, through reduction and condensation leading to simple racemes or spikes and, rarely, to solitary flowers. Bracts and bracteoles usually present, often caducous; bracteoles coloured, enlarged, usually persistent in Amherstieae.
Flowers large to small, often showy, usually bilaterally symmetrical or more or less zygomorphic, less often actinomorphic, bisexual and/or unisexual (then the plants polygamous or dioecious), usually 5-merous except for gynoecium, mostly perigynous, rarely hypogynous. Hypanthium (receptacle) usually present, cupular, tubular, or turbinate, sometimes obscure or absent; the inside often containing nectariferous tissue; other nectar producing organs as discs or other outgrowths at the mouth of the hypanthium. Sepals 5 or 4, free or (infrequently) partly united, usually imbricate. Petals 5, sometimes reduced to 4(--1), or 0, often unequal, the upper being the largest, sometimes vexillum-like; usually imbricate-ascending. Stamens basically 10, rarely through reduction 5, 3, 2, 1 or in female flowers 0, rarely many; filaments free or variously connected at basal parts; anthers variously developed, basi- or dorsifixed, often versatile, longitudinally dehiscent, rarely by (apical or basal) pores. Gynoecium usually stipitate, rarely sessile, the gynophore often partly adnate to the adaxial wall of the hypanthium. Ovary with (1--) few to many anatropous, often superposed ovules in 2 rows on either side of the adaxial suture; style short or long, often curving inward; stigma large or small, capitate or peltate, sometimes obscure.
Fruits variable, usually oblong to linear or strap-shaped, laterally compressed, straight or curved, dehiscent and 2-valved, valves chartaceous, fleshy, coriaceous, thick, or woody; indehiscent and drupaceous or samaroid; with or without pulp; glabrous, hairy, or spiny (wallichii Sind pods HookIc1018 ).
Seeds varying in shape, often flattened; testa membranous, coriaceous, or crustose; sometimes arillate (); endosperm present or lacking; cotyledons fleshy or foliaceous; radicle straight or slightly oblique, never folded.
Distribution
The Caesalpinioideae are a predominantly tropical group of c. 160 genera with c. 2000 species. The greatest number of genera is found in tropical Africa and tropical America. In Malesia there are 25 indigenous genera, containing 189 native species and more than 20 cultivated, introduced, or naturalized ones. In addition there are also at least eight commonly introduced or widely cultivated genera with nine species.
Very few genera occur in the subtropical zones and only 3 reach the temperate regions, i. e. Cercis , Ceratonia and Gleditsia ; the last one is also represented in Malesia.
The largest genus is Bauhinia with more than 300 species throughout the tropics, it has 70 species in Malesia, c. 60 in Indochina and 40 in S China. Several species are endemics of very restricted distribution. Cassia is mainly neotropic and so are the segregate genera Senna and Chamaecrista . Caesalpinia is pantropic with 19 indigenous species in Malesia. Most other genera are relatively small and several restricted to tropical Asia. Few genera have a disjunct distribution as e. g. Copaifera occurring in tropical America, tropical Africa, and Borneo, and Gymnocladus in eastern N America and eastern Asia.
This subfamily is divided into the following tribes: Tribe Caesalpinieae, Tribe Cassieae, Tribe Cercideae, Tribe Detarieae and Tribe Macrolobieae.