Swietenia with five species is confined to tropical America from southern Florida where one species occurs, to Venezuela, western and southwestern Mexico, and the east coast of Central America.
The generic name is in honor of Baron von Swieten (1700—1772), the distinguished Dutch physician, founder of the Botanic Garden and of the Medical School at Vienna.
1. [Swietenia mahagoni] Jacq. Mahogany.
Leaves 4′—6′ long, with a slender glabrous petiole thickened at base and 3 or 4 pairs of ovate-lanceolate leaflets rounded at base on the upper side, narrow-cuneate or nearly straight on the lower side, entire, coriaceous, pale yellow-green or slightly rufous on the under surface, 3′—4′ long, 1′—1½′ wide, with a prominent reddish brown midrib, conspicuous reticulate veins, and a stout grooved petiolule ¼′ long. Flowers appearing in July and August on slender puberulous pedicels, bibracteolate near the middle, 1 or 2 together at the end of the branches of slender panicles in the axils of leaves of the year; calyx glabrous, cup-shaped, much shorter than the ovate elliptic petals ⅛′ long and slightly emarginate at apex. Fruit ripening in the autumn or early winter, long-stalked, ovoid, rounded at apex narrowed at base, 4′—5′ long and 2½′ broad, with thick dark brown valves rugose and pitted on the surface, its axis obovoid 3′ or 4′ long, 1′—1½′ thick, dark red-brown, marked near the apex by the dark scars left by the falling seeds; seeds ¾′ long, almost square, thickened at base and nearly one fourth as long as their ovate rugose red-brown wings rounded or truncate at apex and gradually contracted below.
A tree, in Florida rarely more than 40°—50° high or with a trunk exceeding 2° in diameter, and slender glabrous angled branchlets covered during their first season with pale red-brown bark, becoming lighter or gray faintly tinged with red and thickly covered with lenticels during their second year; much larger in the West Indies. Winter-buds about ⅛′ long, with broad-ovate minutely apiculate loosely imbricated light red scales. Bark of the trunk in Florida ½′—⅔′ thick, with a dark red-brown surface broken into short broad rather thick scales. Wood heavy, exceedingly hard and strong, close-grained, very durable, rich red-brown, becoming darker with age and exposure, with thin yellow sapwood of about 20 layers of annual growth; the most esteemed of all woods for cabinet-making, and also largely used in the interior finish of houses and railroad cars, and formerly in ship and boat-building. The bark is bitter and astringent and has been used as a substitute for quinine in the treatment of intermittent fevers.
Distribution. Florida, hummocks, shores of Bay Biscayne on the Everglade Keys and near Flamingo on White Water Bay, Dade County, on Elliotts Key, Key Largo and Upper Matacombe Key; rare and now nearly exterminated except in the region of Cape Sable; on the Bahama and many of the West Indian islands.
XXX. EUPHORBIACEÆ.
Trees, shrubs, or herbs, with acrid juice, and alternate stipular leaves. Flowers monœcious or diœcious; calyx 3—6-lobed or parted, the divisions imbricated in the bud, or wanting; corolla 0; stamens 2 or 3, or as many or twice as many as the calyx-lobes; anthers 2-celled, opening longitudinally; ovules 1 or 2 in each cell, suspended, anatropous; raphe ventral; micropyle superior. Fruit a drupe or capsule. Seeds albuminous; cotyledons flat, much longer than the superior radicle.
The Euphorbia family, widely distributed over tropical and temperate regions, with some one hundred and thirty genera and over three thousand species, is represented in the United States by three arborescent genera, with only five species, and by many shrubby herbaceous and annual plants.