Robust perennial herb to 1 m tall, forming large clumps; leaves mostly in 1-3 pairs in the basal 1/4 of the plant, petioles 5-10 cm long, blades broadly ovate to more or less circular, thick, leathery-succulent, glaucous bluish-green, sparsely tuberculate with small, darkened multicellular mounds; inflorescence widely paniculate, forming the distal 3/4 of the plant, the internodes with sticky glutinous bands; flowers borne in few-flowered clusters; perianth funnelform, 5-lobed, slightly zygomorphic, deep rose-pink, about 3 cm long; stamens 3, about twice the length of the perianth, deep rose-pink; style exserted slightly beyond the anthers, deep rose-pink; fruit biturbinate, 5-7 mm long, 3-4 mm wide, with 10 irregular longitudinal ridges and with an equatorial wing 0.2-0.9 mm wide. Flowers June to October.
Anulocaulis leiosolenus var. gypsogenus, from along the Pecos River, differs in its highly glaucous pale blue-gray green smooth leaves, its very pale pink to white flowers, and the fruit with a wing 0.8-1.2 mm wide. Anulocaulis leiosolenus var. leiosolenus, mostly from along the Rio Grande, has green leaves that are notably tuberculate, pale pink flowers, and a wing on the fruit 0.2-0.6 mm wide.
New Mexico, Otero County, west slope of the Guadalupe Mountains.
Open gypsum outcrop of the Yeso Formation, with limestone cobble, at about 1,350-1,450 m (4,425-4,750 ft).
Ranching activities on Crow Flats, the valley to the west of the locality of this ringstem, do not affect the species because, as one rancher noted, cattle don't go onto its habitat; water sources are distant. Plants were noted to be browsed late in the season, very likely by deer whose sign was evident in the area.
Spellenberg, R. 1993. Taxonomy of Anulocaulis (Nyctaginaceae). Sida 15:373-389.
Spellenberg, R. and T. Wootten. 1999. Vascular plants on a gypsum outcrop in southern New Mexico: A listing, a new variety and taxonomic realignments in the Anulocaulis leiosolenus complex (Nyctaginaceae), and a new variety of Mentzelia humilus (Loasaceae). Sida 18(4):987-999.