Ephedra antisyphilitica

Shrubs erect or spreading, 0.25--1 m. Bark gray, slightly cracked and irregularly fissured. Branches alternate or whorled, rigid, angle of divergence about 45°. Twigs green, becoming yellow-green with age, glaucous, not viscid, with numerous longitudinal grooves; internodes 2--5 cm. Terminal buds conic, 1--3 mm, apex obtuse. Leaves opposite, 1--3 mm, connate to 2/3--7/8 their length; bases thickened, brown, completely deciduous; apex obtuse. Pollen cones 1--2 at node, lance-ellipsoid, 5--8 mm, sessile to nearly sessile; bracts opposite, 5--8 pairs, pale green to red, obovate, 2--4 × 2--3 mm, membranous, connate at base; bracteoles slightly exceeding bracts; sporangiophores 4--5 mm, 1/2 exserted, with 4--6 sessile to very short-stalked (less than 1 mm) microsporangia. Seed cones 1--2 at node, ellipsoid, 6--12 mm, sessile to nearly sessile; bracts opposite, 4--6 pairs, ovate, 5--7 × 5--10 mm, connate to 1/8--7/8 their length, inner pairs becoming fleshy and red. Seeds 1(--2), ellipsoid, 6--9 × 2--4 mm, light brown to chestnut, smooth.

Coning March--April. Arid soils and rocky slopes; 100--1200 m; Okla., Tex.; Mexico in Nuevo León and San Luis Potosí.

Mexican populations of Ephedra antisyphilitica are disjunct from those in Texas.