Acleisanthes obtusa

Plants herbaceous, often woody at base, overall pubescence of white, capitate hairs 0.1-0.2 mm. Stems prostrate or spreading, much branched, to more than 100 cm, hirtellous to glabrate. Leaves grayish green, sessile or petiolate, those of pair slightly unequal; petiole to 25 mm, hirtellous to glabrate; blade deltate to deltate-ovate, 2-30(-45) × 2-35(-50) mm, base truncate to subcordate or rounded and short decurrent, margins flat or slightly undulate, apex acute to broadly rounded and often apiculate, puberulent to glabrate. Inflorescences solitary flowers or 2-5-flowered cymes, sessile or with pedicel to 5 mm; bracts linear-subulate, 1-7 mm, puberulent, usually sparsely so. Flowers: chasmogamous perianth 2.5-5.5 cm, sparsely puberulent, tube 1-2 mm diam., limbs 13-25 mm diam., stamens 5; cleistogamous perianth 3-12 mm, puberulent, stamens 5. Fruits 5-ribbed with pair of parallel grooves between ribs, each rib and pair of grooves ending at summit in inconspicuous, glandless knob, oblong, truncate at both ends, often constricted ca. 1 mm above base and below apex, 5-8 mm, hirtellous to sparsely puberulent with capitate hairs and with few, scattered, moniliform hairs 0.2-0.3 mm.

Flowering early spring-late fall. Sandy, silty, or clay soils on calcareous or igneous substrates in grasslands, shrublands, or woodlands; 0-1800 m; Tex.; s to c Mexico.