PLANT: Shrub 0.7–2.5 m tall, rather sparingly branched, with few thorns at the end of branches, or practically unarmed; branches somewhat crooked, decumbent or flexuous, tan to silvery-gray, the older stems often dark reddish brown. LEAVES: glabrous, linear to spatu1ate-obovate, 1.5–6(–15) mm long, 1–2.5(–4.5) mm wide, rounded, sometimes acute or emarginate at the apex, fascicled. FLOWERS: solitary or in groups of 2–3 in the leaf fascicles; pedicels 3–20 mm long; calyx cup-shaped, 1–3 mm long, 3–5-lobed, the lobes deltoid, about one third as long as the tube, equal or unequal, the calyx frequently splitting to the base on one side, with a small tuft of hair at the tip of each lobe; corolla white or pale lavender, obconic-funnelform, constricted immediately above the ovary, 4–9 mm long, the lobes 4–5, 1/6–1/3 the length of the tube, usually reflexed; stamens unequal or subequal, included to longexserted; filaments adnate to a point between 1/3 and nearly 1/2 the length of the corolla-tube, hairy for the first third of their free portion, adjacent corolla-tube hairy, the portion below the insertion of the filaments from almost glabrous to densely hairy; style equaling the stamens in length or surpassing them. FRUITS: globose, 5 mm in diameter, many-seeded (Fig. 2J). NOTES: Sonoran Desert, along washes: La Paz, Maricopa, Pima, Pinal, Santa Cruz, Yavapai,Yuma cos. (Fig. 1B); 350–900 m (1200–3000 ft); mainly Jul–Sep, but occasionally at other times; s CA to TX, OK; s to Tamps., S.L.P., Hgo., and Baja C. Sur, Mex. REFERENCES: Windham, M.D. And G. Yatskievych. 2009. Vascular Plants of Arizona: Isoëtaceae. CANOTIA 5 (1): 27–29, 2009.