2. EXOSTEMA Rich.
Trees or shrubs, with terete branchlets, and bitter bark. Leaves sessile or petiolate, persistent; stipules interpetiolar, deciduous. Flowers axillary and solitary or in terminal pedunculate cymes, fragrant, the peduncle bibracteolate above the middle; calyx-tube ovoid, clavate or turbinate, the limb short, 5-lobed, the lobes nearly triangular, persistent; corolla 5-lobed, white, salver-form, the tube long and narrow, erect, the lobes of the limb linear, elongated, spreading, imbricated in the bud; filaments filiform, exserted, united at base into a tube inserted on and adnate to the tube of the corolla; anthers oblong-linear; ovary 2-celled; style elongated, slender, exserted; stigma capitate, simple or minutely 2-lobed; ovules numerous, attached on the 2 sides of a fleshy oblong peltate placenta fixed to the inner face of the cell, ascending. Fruit a many-seeded 2-celled capsule septicidally 2-valved, the valves 2-parted, their outer layer membranaceous, separable from the crustaceous inner layer. Seeds compressed, oblong, imbricated downward on the placenta; seed-coat chestnut-brown, lustrous, produced into a narrow wing; embryo minute, in fleshy albumen; cotyledons flat; radicle terete, inferior.
Exostema with about twenty species is confined to the tropics of America, and is most abundant in the Antilles, one species reaching the shores of southern Florida. The bark contains active tonic properties, and has been used as a febrifuge.
The generic name, from ἔξω and στῆμα, relates to the long exserted stamens.
1. [Exostema caribæum] R. & S. Prince Wood.
Leaves oblong-ovate to lanceolate, contracted into a slender point and apiculate at apex, gradually narrowed and cuneate at base, entire, thick and coriaceous, dark green on the upper surface and yellow-green on the lower surface, 1½′—3′ long and ½′—1¼′ wide, with a prominent orange-colored midrib and conspicuous reticulate veinlets; unfolding in the autumn and in early spring and summer, and persistent for 1 or 2 years; petioles slender, orange-colored, ¼′—½′ in length; stipules nearly triangular, apiculate, with entire dentate or ciliate margins, about 1/16′ long, and in falling marking the branchlets with ring-like scars. Flowers axillary, solitary, appearing from March until June, about 3′ long, on slender pedicels spirally twisted before the flowers open; calyx-tube ovoid; corolla glabrous; filaments united into a short tube. Fruit ⅔′ long, becoming black in drying; seeds oblong, ⅛′ long, with a dark brown papillose coat and a light brown wing.
A glabrous tree, in Florida sometimes 20°—25° high, with a trunk 10′—12′ in diameter, slender erect branches forming a narrow head, and terete branchlets dark green at first, soon becoming dark red-brown and covered with pale lenticels, and in their second year ashy gray and conspicuously marked by the elevated leaf-scars. Bark of the trunk about ⅛′ thick, and divided by deep fissures into square smooth pale or nearly white plates. Wood very heavy, exceedingly hard, strong, close-grained, light brown handsomely streaked with different shades of yellow and brown, with bright yellow sapwood of 12—20 layers of annual growth.
Distribution. Florida, shores of Bay Biscayne and on the Everglade Keys, Dade County, and on the southern keys; abundant on Key West and Upper Metacombe Key; on many of the Antilles, in southern Mexico, and on the west coast of Nicaragua.