Rosidae: Fabales. The Caesalpiniaceae are mostly tropical and subtropical trees and shrubs comprising about 150 genera and 2,200 species. The leaves are stipulate, alternate, and mostly pinnately compound but may be bipinnate or simple. Like the other legume families the petiole base is commonly enlarged into a pulvinus. 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. The pistil is simple, consisting of one style and stigma, and a superior ovary with one locule containing 2-many marginal ovules. The fruit is usually a legume.

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


Cercis occidentalis, red bud. Note the bilateral floral symmetry and the posterior petal interior to the lateral ones.
Bauhinia variegata, 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.
Bauhinia galpinii. Ornamental climbing shrub from Africa.
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.
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.
Cassia fistula, golden shower tree. Notice the posterior petal innermost and three stamens reduced to staminodes.
Tamarindus indica, tamarind. Note the strong bilateral symmetry, the posterior petal innermost, and the 3 functional stamens.
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.
Colvillea racemosa, colvillea. Large showy tree from Madagascar.
Caesalpinia kavaiensis, uhiuhi. This is a rare Hawaiian endemic species of the family.

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