XLIX. MELASTOMACEÆ.
Trees, shrubs, or herbs with watery juice. Leaves opposite, rarely verticellate, 3—9-nerved, usually petiolate; stipules 0. Flowers regular, perfect, usually showy, rarely fragrant, in terminal clusters; calyx usually 4 or 5-lobed, the lobes imbricated in the bud; petals as many as the lobes of the calyx, inserted on its throat, imbricated or convolute in the bud; stamens as many or twice as many as the petals, inserted in 1 series with them, often inclined or decimate; anthers 2-celled, attached at the base, opening by a terminal pore; ovary 2 or many-celled; style terminal, simple, straight or declinate; stigma capitate, simple or lobed; ovules numerous, minute, anatropous. Fruit capsular or baccate, inclosed in the calyx-tube; seeds minute; testa coriaceous or crustaceous; hilum lateral or basal; embryo without albumen.
This family with 164 genera and a large number of species is chiefly confined to the tropics, and is most abundant in those of South America.
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.