Exostema caribaeum (Jacq.) Roem. & Schult.
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Authority
Britton, Nathaniel L. Flora Borinqueña.
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Family
Rubiaceae
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Scientific Name
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Description
Species Description - The bitter bark of this small tree, or shrub, is sometimes used as a febrifuge, in domestic medicine, as a substitute for the drug quinine, derived from the bark of the related Cinchona trees, natives of the South American Andes, and extensively planted in tropical Asia. The natural distribution extends from Florida and the Bahamas nearly throughout the West Indies, and from Central Mexico to Costa Rica. In Porto Rico the tree is restricted to the dry southern districts, ascending on the mountain-sides to about 150 meters altitude, perhaps higher, and grows also on the small islands Mona, Cayo Muertos, Vieques and Culebra. The long, quite large, white or purplish flowers are attractive. The tree was first described botanically from specimens collected in Cuba or Santo Domingo. Exostema (Greek, exserted stamens), a genus proposed by A. Richard, and published by Humboldt and Bonpland in 1807, comprises about 30 species of trees and shrubs, natives of tropical America, with opposite, stalked, untoothed leaves, and solitary or clustered flowers. The calyx has a cylindric or top-shaped tube, adnate to the ovary, with 5, narrow lobes; the salver-form corolla has a slender, cylindric tube and 5, long lobes; there are 5 stamens, with long, very slender filaments and narrow anthers; the 2-celled ovary contains many ovules, and the style is long and slender. The fruit is a capsule, splitting when ripe into 2 valves, releasing the numerous, small, winged seeds. Exostema caribaeum (of the Caribbean Islands) is a small tree, with maximum height of about 8 meters with a trunk up to about 10 centimeters in diameter, usually smaller, and often shrubby, its bark narrowly ridged and fissu[r]ed, the foliage smooth. The rather thin leaves are oblong or elliptic, slender-stalked, pointed, from 3 to 8 centimeters long, with a prominent midvein, and few, obscure lateral veins. The flowers are solitary and short-stalked in the leaf-axils; the nearly cylindric calyx is 4 or 5 millimeters long, with short lobes; the tube of the corolla is from 2 to 3 centimeters long, slightly longer than its narrow lobes; the anthers are long-exserted. The oblong, smooth, woody capsule is from 10 to 15 millimeters long. Exostema ellipticum, found by Professor Cowles above Villalba in 1925, is also illustrated in this work. Another species, Exostema sanctae-luciae, with clustered, red flowers, and larger leaves, 10 to 22 centimeters long, was found many years ago in the forest on Monte Alegrillo, near Maricao; it inhabits Cuba, Santo Domingo and the southern Lesser Antilles, first made known from St. Lucia.
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Discussion
Cuero de Sapo Prince-wood Madder Family Cinchona caribaea Jacquin, Enumeratio Systematica Plantarum 16. 1760. Exostema caribaeum Roemer & Schultes, Systema Vegetabilium 5:18.1819.