Plants annual or perennial, herbaceous, glabrous or densely stipitate-glandular, not glaucous. Stems sprawling, branching proximally, 10-30+ cm. Leaves opposite; stipules ± persistent, di-vided into 2 or 3 filiform segments, 0.5-3.5 mm; petiole (1-)3-6 mm; blade broadly ovate, deltate, cordate, or reniform, (0.2-)0.5-1.6 cm × 4-12 mm, base truncate to rounded, apex acute to cuspidate. Inflorescences terminal, open, 3-15-flowered cymes. Pedicels shorter to longer than subtending bracts at maturity. Flowers: sepals with 3 distinct veins arcing outward at midsection and ± confluent apically, lance-ovate to elliptic (herbaceous portion linear-lanceolate to narrowly ovate), 3-4(-5) mm, subequal, apex acute to acuminate (herbaceous portion often obtuse), not hooded, glabrous; petals 2-fid for 1/ 3/ 4 their length, 2.7-6 mm, subequal to sepals, lobes 1-veined, vein dichotomously branched distally, oblong, trunk entire, base abruptly tapered, apex deeply notched. Seeds dark brown to blackish, snail-shell-shaped, 0.5-0.7 mm; tubercles prominent, conic. Flowering spring-late fall. Montane chaparral and woodlands, igneous-rock mountains; 1400-2500 m; Tex.; Mexico (Chihuahua, Coahuila, San Luis Potosí, Zacatecas).