Phytoneuron 2014-11: 15, fig. 9. 2014.
Stems glabrous; tendrils unbranched. Leaves 3-foliolate, lateral pair of leaflets deeply lobed, petiolules 2–5 mm, terminal leaflet 3–5 cm, blade narrowly lanceolate, petiolule 3–12 mm, narrowly oblanceolate, gradually broadening into leaflet base, leaflet margins coarsely serrate; petioles 16–28 mm. Staminate inflorescences (0.5–) 2–12 cm, floriferous portion (0.5–) 1.2–6 cm, (12–) 18–70-flowered, narrowly racemoid, with racemose or fasciculate lateral branches 3–7 mm; flowers solitary or in fascicles of 2–3. Staminate corollas 3.8–6.3 mm diam. Anther heads 0.6–1 mm diam., sessile, glabrous. Fruiting peduncles 2–7 mm. Capsules ovoid, distinctly oblique-gibbous, short-beaked, (12–) 15–20 mm, spinules (2–) 3–5 mm.
Phenology: Flowering (May–)Aug–Oct.
Habitat: Canyons, rocky slopes, among boulders, igneous soil, roadsides, pinyon-oak-juniper woodlands
Elevation: 1100–2500 m
Cyclanthera stenura is distinct from C. gracillima in the more elongate and profusely flowered floriferous portion of its staminate inflorescence and its geography. It occurs in Brewster, Jeff Davis, and Presidio counties of the Trans-Pecos region of Texas.
"/3" is not declared as a valid unit of measurement for this property.