1. TETRAZYGIA A. Rich.
Trees or shrubs, with terete branchlets. Leaves opposite, petiolate, oblong-ovate to ovate-lanceolate, entire or denticulate, 3—5-nerved, persistent, scurfy, like the young branchlets, peduncles and calyx-tube. Flowers perfect in many-flowered terminal panicles or corymbs; calyx-tube urceolate or globose, adnate to the ovary, the limb constricted above the ovary and dilated below the apex, the lobes short or elongated; petals obovate, obtuse, convolute in the bud; stamens twice as many as the petals; filaments subulate; anthers linear-subulate, erect or slightly recurved, attached at base, 2-celled, opening by a minute pore at apex, their connective not extended below the cells; ovary 3—6-celled; style filiform, curved, exserted, surrounded at base by a short sheath 8—10-toothed at apex; ovules indefinite, minute, sessile on an axile placenta. Fruit a 3 or 4-celled berry, crowned by the persistent tube of the calyx; seeds numerous, minute, obpyramidal, thickened and incurved at apex; testa coriaceous, slightly pitted; hilum basal; cotyledons thick; radicle short, turned toward the hilum.
Tetrazygia with 14 species is confined to the West Indies and southern Florida where one species has been discovered, the only tree of the great family of the Melastomaceæ found in the United States.
The generic name is from τέτρα and ζυγόν in allusion to the often 4-parted flowers.
1. [Tetrazygia bicolor] Cogn.
Leaves oblong-lanceolate, acuminate, gradually narrowed and rounded at base, 3-nerved, entire, undulate and slightly thickened on the revolute margins, dark green on the upper surface, paler on the lower surface, 3′—4½′ long and 1′—1¾′ wide; petioles stout, ¾—1′ in length. Flowers appearing from March to May, ⅘′ in diameter, short-stalked, in open cymose panicles; calyx urceolate, 4 or 5-lobed, the lobes nearly obsolete; petals 4 or 5, oblong-obovate, reflexed after anthesis, white; ovary 3-celled, style surrounded at base by a short sheath 10-toothed at apex. Fruit ripening in late autumn or early winter, oblong to ovoid, conspicuously constricted at apex, ¼′—⅓′ in length and ⅙′—⅕′ in diameter.
In Florida a shrub, or in the dense woods of the keys of the Everglades a slender tree, often 30° high, with an erect trunk 3′ or 4′ in diameter, covered with thin light gray-brown slightly fissured bark, small spreading branches becoming erect toward their apex and gracefully drooping leaves; or in the sandy soil of open Pine-woods often less than 3° in height.
Distribution. Florida, on the Everglade Keys, Dade County; on the Bahama Islands and in Cuba.