1. Acleisanthes anisophylla A. Gray, Amer. J. Sci. Arts, ser. 2. 15: 261. 1853.
Plants herbaceous, overall pubescence of white, capitate hairs 0.1-0.2 mm. Stems decumbent, much branched, 3-15 cm, puberulent to glabrate. Leaves grayish green, sessile or more often petioled, those of pair very unequal (1 leaf 2-10 times length of other); petioles of smaller leaves to 12 mm, those of larger leaves 2-35 mm, puberulent to glabrate; blade ovate to oval-oblong or oval-rhombic, base rounded to obtuse, unequal and short decurrent, margins flat or very slightly undulate, apex acute to rounded or obtuse and apiculate, puberulent to glabrate; smaller blades 3-28 × 2-15 mm, larger blades 6-70 × 3-35 mm. Inflorescences solitary flowers, sessile or pedicellate; bracts linear-lanceolate to linear-subulate, 2-6 mm, sparsely puberulent; pedicel to 1 mm. Flowers: chasmogamous perianth 4-6 cm, puberulent, tube 10 mm diam., limbs 20-40 mm diam., stamens 5; cleistogamous perianth 1-3 mm, puberulent, stamens 5. Fruits with 10 equal ribs, without resinous glands, oval-oblong, truncate at both ends, slightly constricted beyond base, 3-6 mm, sparsely puberulent.
Flowering spring-fall. Rocky, gravelly, or sandy soils, limestone or shale outcrops in grasslands or shrublands; 40-3500 m; Tex.; Mexico (Coahuila, Nuevo León, Tamaulipas).