11. Tripterocalyx (Torrey) Hooker, Hooker’s J. Bot. Kew Gard. Misc. 5: 261. 1853.
Sand-puffs [Greek tri, three, pteron, wing, and calyx, in reference to the perianth]
Leo A. Galloway
Abronia Jussieu [unranked] Tripterocalyx Torrey in J. C. Frémont, Rep. Exped. Rocky Mts., 92. 1843
Herbs, annual, viscid pubescent to nearly glabrous, from slender or stout and ± woody taproots. Stems decumbent to semierect, unarmed, without glutinous bands on internodes. Leaves petiolate, unequal in size in each pair; blade ± thick and succulent, base usually asymmetric. Inflorescences axillary, pedunculate, capitate clusters; receptacle flat to somewhat rounded-conic, with short, pedicel-like projections; flowers maturing from one side of inflorescence to other; bracts persistent, not accrescent, 5-10, distinct, thin and translucent, forming an involucre, linear-lanceolate to ovate, broad. Flowers bisexual, chasmogamous; perianth radially symmetric, funnelform or salverform, constricted beyond ovary, abruptly expanded to 4-5-lobed limb; stamens (3-)4-5, included; styles included; stigmas linear. Fruits fusiform, indurate throughout, or spongy on exterior, minutely puberulent or glabrous; wings 2-4, translucent, prominently veined, scarious, extending beyond apex and/or base of body; sulci smooth or coarsely rugose.
Species 4 (4 in the flora): North America (including n Mexico).
Galloway, L. A. 1975. Systematics of North American desert species of Abronia and Tripterocalyx. Brittonia 27: 328-347.