2. Anulocaulis eriosolenus (A. Gray) Standley, Contr. U.S. Natl. Herb. 12: 375. 1909.
Boerhavia eriosolena A. Gray, Amer. J. Sci. Arts, ser. 2, 15: 322. 1853
Herbs, stout or slender, short-lived perennial or annual. Stems 0.2-1.8 m. Leaves: 2-3 pairs near base; petiole 2-7 cm; blade broadly ovate to almost round, 2-11 × 2-13 cm, base shallowly cordate to ± truncate, apex rounded or obtuse, adaxial surface yellow-green, abaxial surface much paler, both surfaces sparsely villous-hispid with blackish based hairs. Flowers usually borne singly on branchlets of inflorescence; perianth 8-9 mm, tube white to pink or pale lavender [magenta], finely pubescent, limbs white to pink or pale lavender [magenta], gradually flared from tube; stamens 5, exserted 4-6 mm. Fruits bluntly 5-angled, turbinate, 2.6-3.8 × 2.4-3.4 mm, sometimes secreting mucilage (especially southern populations) when wetted; ribs 10, faint, linear; equatorial flange or ridge absent. 2n = 24.
Flowering late spring-mid fall. Sandy, gravelly limestone outwash fans, or calcareous silty soils, gypsum; 600-1200 m; Tex.; Mexico (Chihuahua, Coahuila).
The perianth tube of Anulocaulis eriosolenus elongates two to seven times its length after the limb of the perianth wilts.