1. Tripterocalyx micranthus (Torrey) Hooker, Hooker’s J. Bot. Kew Gard. Misc. 5: 261. 1853 (as micrantha).
Abronia micrantha Torrey in J. C. Frémont, Rep. Exped. Rocky Mts., 92. 1843
Stems reddish, glandular-pubescent, ± viscid. Leaves: petiole 1-4 cm; blade lance-ovate to elliptic, 1-6 × 0.5-2.5 cm, margins entire or sinuate, ciliate; surfaces short glandular-pubescent, ± viscid, abaxial surface green or glaucous, adaxial surface green. Inflorescences 5-15-flowered; bracts lanceolate to ovate, 3-9 × 1-3 mm, thin and green or ± papery, base ± attenuate, margins glandular-puberulent, often ciliate, or glabrate to lightly glandular-puberulent. Perianth: tube greenish to pink, 6-18 mm, limb greenish to pink, 3-5 mm diam., lobes inconspicuous. Fruits oval to round in profile, 10-20 × 10-20 mm, walls ± spongy on exterior, indurate on interior, ± smooth to rugose; lateral ribs, if extending into wings, only slightly raised; wings (2-)3(-4).
Flowering spring-fall. Sandy soils, desert scrub, desert grasslands; 800-2400 m; Alta., Sask.; Ariz., Calif., Colo., Kans., Mont., Nev., N.Mex., N.Dak., S.Dak., Utah, Wyo.
The name Abronia cycloptera A. Gray is illegitimate, based on an attempt by Gray to rename A. micrantha Torrey. Gray believed A. micrantha to be a "precociously fertilized state" of what is here recognized at T. carneus.