Description: Trees, shrubs or rarely vines or herbs, sometimes armed with prickles or spines.
Leaves mostly pinnate or sometimes bipinnate, rarely 1-foliolate, simple or reduced to phyllodes; petiole and rachises occasionally with jugary and interjugary glands; stipules, if present, small and caducous.
Inflorescences racemes, spikes or cymes; flowers small to more often larger and ± showy; bracteoles small or absent. Flowers mostly slightly zygomorphic. Sepals usually free, commonly imbricate. Petals ± equal, free, upper one usually borne internally to the adjacent lateral petals. Stamens mostly 10 or fewer by reduction to staminodes, often of unequal size and long-exserted; anthers usually opening by terminal pores or longitudinal slits.
Fruit commonly a pod, often with transverse partitions, ± elongate, often compressed, sometimes winged or spiny; seeds sometimes arillate.
Distribution and occurrence: World: c. 150 gen., >2500 spp., chiefly trop. & subtrop. regions. Aust.: c. 22 gen., 127 spp., all States except Tas. This subfamily is often treated as the family Caesalpiniaceae.
This subfamily is often treated as the family Caesalpiniaceae.
The subfamily includes a number of highly ornamental trees and shrubs, some economically significant, e.g. Tamarindus indica L. (the Tamarind) and Ceratonia siliqua L. (the Carob); a number of non-Australian species yield timber.
**Barklya and **Bauhinia are in the genus key but they are not treated further as records for this State have not been substantiated. Barklya syringifolia F. Muell., a species endemic in Qld, has leaves with lamina broad-ovate and 3-9 cm long, the petiole 3-8 cm long and prominent swellings at the base and apex. Lysiphyllum was previously recorded as occurring in this State (see Flora of NSW, 1991), however, this genus is now included in Bauhinia (see Flora of Australia, Volume 12, 1998); these species have leaves with 2 leaflets or leaves simple and deeply lobed.
| ||Key to the genera|| |
|1||Spines or prickles present.||2|
|Spines or prickles absent.||4|
|2||Erect trees or shrubs with branched or simple straight spines; leaves bipinnate and/or pinnate.||3|
|Shrubs, vines or scramblers with simple recurved prickles; leaves bipinnate.|
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|3||Spines usually >2 cm long; leaflets >10 mm long, not caducous; rachis terete; petals <5 mm long; pods >15 cm long.||Gleditsia|
|Spines <2 cm long; leaflets <5 mm long, often caducous; rachis flattened, 2–3 mm wide; petals c. 10 mm long; pods <10 cm long.|
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|Leaves pinnately or palmately compound (leaflets 1-many) or rarely simple or reduced to phyllodes.|
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|5||Pods >20 cm long; stipules usually pinnate, 5–10 mm long; petals 2–3 cm long, stamens >7 cm long and strongly exserted.||Delonix|
|Pods <10 cm long; stipules ovate, 3–5 mm long; petals and stamens 5–7 cm long, stamens not exserted.|
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|6||Leaves simple or apparently 1-foliolate, petiole about as long as lamina.||Barklya|
|Leaves pinnately or palmately compound, or if reduced to phyllodes or apparently simple then petiole much shorter than lamina.|
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|7||Leaves imparipinnate; fertile anthers 3; style flat and petal-like, forming a pouch over the ovary.||Petalostylis|
|Leaves paripinnate or reduced to phyllodes or leaflets 2 and venation palmate; other characters not as above.|
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|8||Leaflets 2, venation palmate; stigma peltate; stipe fused to floral tube.||Bauhinia|
|Characters not as above, or if leaflets 2 then venation not palmate.|
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|9||Flowers predominantly unisexual, small (sepals <2 mm long), arranged in many-flowered catkin-like racemes; petals absent, flowers reddish.||Ceratonia|
|Flowers bisexual, larger, in few- to many-flowered racemes; petals yellow, rarely spotted with red, >5 mm long.|
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|10||Floral bracteoles 2; stamens not bilaterally symmetric; pods elastically dehiscent with spirally coiled valves.||Chamaecrista|
|Floral bracteoles 1 or absent; stamens bilaterally symmetric; pods never elastically dehiscent.|
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|11||Inflorescences terminal; bracteoles 1; longest anther filaments S-curved, anthers versatile, never beaked; tree, rare, confined to rainforest.||Cassia|
|Inflorescences axillary; bracteoles absent; longest anther filaments C-curved, anthers basifixed, often some beaked; shrubs, subshrubs or herbs, widespread in open forest and shrubland.|
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