1. Phyllanthopsis arida (Warnock & M. C. Johnston) Vorontsova & Petra Hoffmann, Kew Bull. 63: 47. 2008.
Savia arida Warnock & M. C. Johnston, SouthW. Naturalist 5: 3. 1960; Andrachne arida (Warnock & M. C. Johnston) G. L. Webster
Shrubs, dioecious, (2–)4–6(–10) dm. Stems highly branched, branches spreading, longest leafy branchlets to 10 cm. Leaves: petiole 0.5–3 mm; blade elliptic, 4–10 × 3–6 mm, base cuneate to rounded, apex acute to rounded or mucronate, both surfaces pilose; secondary vein pairs 1–3, obscure. Inflorescences: staminate flowers usually solitary, sometimes 2–3 per fascicle; pistillate flowers usually solitary, rarely 2 per fascicle. Staminate flowers: sepals oblong to obovate, 1–1.5 mm; petals 0.8–1 mm; nectary 10- or irregularly crenulate; pistillode pilose. Pistillate flowers: sepals elliptic to oblong, 1–1.5 mm; petals 0.4–0.6 mm; nectary 5- to 10-crenate; pistil 3(–4)-carpellate. Capsules subglobose, 5–6 mm diam., shallowly 3(–4)-lobed; columella 2 mm. Seeds dark brown, 2.5–3 mm; caruncle absent.
Flowering and fruiting Jul–Sep. Scrub and rock crevices, limestone; of conservation concern; 1000–2500 m; Tex.; Mexico (Chihuahua, Coahuila).
Phyllanthopsis arida is rare; populations are highly localized, known only from El Solitario and the Dead Horse Mountains in the Big Bend region of Texas and two localities in nearby Mexico. Its distribution may be relictual (B. H. Warnock and M. C. Johnston 1960).