Monographs Details: Sciacassia siamea (Lam.) Britton
Authority: Britton, Nathaniel L. Flora Borinqueña.
Family:Caesalpiniaceae
Description:Species Description - This rapidly growing tree, with dense foliage and large clusters of large yellow flowers was introduced into Porto Rico by the Forest Service about 1924, and subsequently distributed, locally much planted for shade and ornament, and spontaneous from seed, as at Ciudad Nueva. It is a native of the East Indies. Mr. Barbour has indicated its value as a wind-break. Sciacassia (shade-Cassia) a genus proposed by Doctor Britton in 1930, after prolonged studies of this family of plants with the late Doctor J. N. Rose, includes a few species of Old World trees. They have once-compound leaves, without glands, and large clusters of flowers. There are 5, broad sepals, 5, inconspicuously veined petals, usually 7, perfect stamens and 3 imperfect ones, (staminodes); the anthers open by terminal pores; the slender ovary contains many ovules. The leathery, narrow, flat pod splits tardily into 2 valves, releasing the seeds. Sciacassia siamea (from Siam) is a tree from 8 to 12 meters high, with finely hairy twigs and flower-clusters. Its short-stalked leaves have from 6 to 14 pairs of oblong to oblong-lanceolate, nearly or quite smooth, netted-veined leaflets, from 3 to 7 centimeters long, and 1 or 2 centimeters wide, rather firm in texture, blunt, or notched. The flower-clusters are large and loose, the individual flowers on stalks 3 centimeters long, or shorter, with bractlets 5 or 6 millimeters long; the nearly orbicular sepals are 6 or 7 millimeters long; the clawed petals are bright yellow, from 12 to 16 millimeters long. The pod is from 20 to 25 centimeters long, from 10 to 15 millimeters wide, tipped, and with thickened margins.

Discussion:Siamese Cassia Senna Family Cassia siamea Lamarck, Encyclopédie Méthodique Botanique 1: 648. 1785. Cassia florida Vahl, Symbolae Botanicae 3: 57. 1794. Sciacassia siamea Britton; Britton and Rose, North American Flora 23: 252. 1930.
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