in H. Krainz et al., Kakteen 62: CIIa. 1975.
Shrubs, suberect to sprawling, very inconspicuous. Roots 12 or more, ending in sweet potato-like swellings, 10–15 × 4–7 cm. Stems greenish brown to brown, branched, 25–75(–100) cm, distally 6 mm diam., at midlength ca. 6 mm diam.; wood hollow, solid-surfaced cylinders, proximally 3–7 mm diam.; ribs 6–9, flat-topped to 2 mm broad, narrowing toward sinus, 0.5 mm deep, separated by narrow grooves; areoles 5–20 mm apart along ribs, circular, 1 mm diam. Spines 5–12 per areole, yellowish white, some with black tips, nearly acicular, weak and easily broken off, 1.5–4 mm; radial spines encircling central spines, abaxial 3 longest, appressed, scurfy when young; central spines 2–3 porrect. Flowers: nocturnal, 7–10 cm; scales of flower tubes green-purple to reddish; outer tepals reddish to green-purple; inner tepals white to lightly tinted rose, lanceolate to oblanceolate, 2 cm, attenuate to apiculate; stamens 1 cm; anthers pale lemon yellow, 1.5–2 mm; style yellow-white, 6 cm; stigma lobes 9, yellowish white. Fruits scarlet, pyriform, 40–50 × 25 mm, with bristlelike spines. Seeds 1 × 0.8 mm; testa pitted near hilum.
Phenology: Flowering summer; fruiting summer–early fall.
Habitat: Sonoran Desert, flats, small hills
Elevation: 0-500 m
Ariz., Mexico (Baja California Sur, Sinaloa, Sonora).