The Caesalpinioideae are mostly tropical and subtropical trees and shrubs comprising about 150 genera and 2,700 species. The leaves are pinnate, bipinnate, or rarely simple. The flowers are in racemes, spikes or cymes, are zygomorphic, and are mostly weakly to strongly perigynous. The perianth commonly consists of a calyx and corolla of 5 segments each; the petals are distinct, overlapping (i.e., imbricate) in bud, with the posterior one (flag or banner) innermost in position. The androecium usually consists of 1-10 distinct or variously united stamens, some of which are commonly reduced to nonfunctional staminodes.  Pollen released as monads.  Seeds usually lack u-shaped line (pleurogram).

Each "thumbnail" image below is linked to a larger photograph.

Bauhinia galpinii. Ornamental climbing shrub from Africa. Note the very small staminodes in addition to the three much larger functional stamens.
Bauhinia x blakeana, Hong Kong orchid tree. Note the bilateral symmetry of the flower and the position of the posterior petal, which is different in size and coloration in this case. Note also the 5 apparent stamens and the simple leaves. UH Campus, Honolulu.
Bauhinia purpurea, UH campus, Honolulu, May, 2004.
Bauhinia variegata, orchid tree, UH campus, Honolulu, April, 2004.
Brownea coccinea, scarlet flame bean. Small tree from tropical america with large clusters of bright orange-red flowers 6-8 inches in diameter borne mostly on the larger limbs.
Brownea sp., Foster Garden, Honolulu, HI, April, 2004
Caesalpinia kavaiensis, uhiuhi. This is a rare Hawaiian endemic species of the family.
poi_pul_cus.jpg (9585 bytes)
Caesalpinia pulcherrima, Caesalpiniaceae, Barbados pride, dwarf poinciana. Prickly shrub or small tree from the West Indies with pinnate leaves. Note the typical legume (monocarpous but splits into two segments). The green seeds may be eaten when cooked, and when ripe yield tannin and yellow (with alum) or black (with iron) dye.
Cassia bakeriana, Caesalpiniaceae, pink shower tree.  Showy ornamental tree from tropical Asia. Univ. Hawaii, Manoa Campus, April, 2005.
Cassia fistula, golden shower tree. Notice the posterior petal innermost and three stamens reduced to staminodes.
Cassia marginata, red shower tree, red or rose cassia.
Cercis occidentalis, red bud. Note the bilateral floral symmetry and the posterior petal interior to the lateral ones.
Chamaecrista nictitans, partridge pea.  Kealia Tr., Oahu, 2005.
Colvillea racemosa, colvillea. Large showy tree from Madagascar.
Delonix regia, royal poinciana, flame tree, 'ohai-'ula. Small to mid-sized tree from Madagascar, with a flat to umbrella-shaped canopy and brilliant, orange-red flowers, commonly planted in Hawaii as a street tree. Note the actinomorphic calyx of 5 radially disposed sepals that are red on the inner face and the zygomorphic corolla with the posterior petal (banner or flag) differentiated from the others.
Haematoxylon campechianum, logwood.  The heartwood is used to produce dyes, inks, and also stains for cytological preparations.  3-5, Foster Botanic Garden, Honolulu, April, 2004.
Peltophorum pterocarpum, yellow poinciana.
Saraca indica, asoka, sorrowless tree, calyx developed into a tubular, corolla-like structure, subtended by two calyx-like bracts; stamens borne on the margin of the calyx; pistil united below to one side of the calyx tube.
Senna surattensis, kolomona. Note the distinct petals, the posterior petal innermost, and the androecium consisting of a mixture of apparently functional and nonfunctional stamens. The ovary is visible as an upcurved green structure in the lower portion of the strongly bilateral flower.
Tamarindus indica, tamarind. Note the strong bilateral symmetry, the posterior petal innermost, and the 3 functional stamens.

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