Plants annual (sometimes short-lived perennial), monoecious, sprawling, trailing, or climbing; stems annual, glabrate; taprooted or roots slender-fibrous; tendrils unbranched. Leaves: blade hastate, 4–5-angular, or suborbiculate, shallowly to deeply palmately 3(–5)-lobed, lobes triangular or ovate to linear-oblong, central lobe usually longest, margins entire, surfaces eglandular. Inflorescences: staminate flowers (1–)2(–3) in axillary racemes or racemoid panicles; pistillate flowers solitary in same axils as staminate, irregularly produced; peduncles erect at apex; bracts absent. Flowers: hypanthium cupulate; sepals 5, barely differentiated as apiculae; petals 5, distinct or nearly so, white, triangular to ovate or narrowly oblong-triangular with acute apices, 1–1.5[–3] mm, glabrous, corolla rotate to shallowly cupulate. Staminate flowers: stamens 3–5 (appearing 1–3 from connation); filaments inserted at hypanthium base, connate; thecae connate, forming a head but not fused into ring, horseshoe-shaped, twisted-contorted, connective broad; pistillodes absent. Pistillate flowers: ovary 1-locular, broadly fusiform-rostrate; ovules 1(–2) per locule; styles 1–3, columnar; stigmas 1, depressed-globose to hemispheric, sometimes 2-lobed; staminodes absent. Fruits capsular, light tan, obovoid to suborbicular, gibbous, slightly compressed, beaked, dry, thin-walled, sparsely short-echinate or subaculeate, spinules thick-based, antrorsely upturned, irregularly dehiscent. Seeds 1(–2), subcylindric-clavate to obdeltoid, compressed, not arillate, margins not differentiated, surface muriculate to warty.
sw United States, nw Mexico.
J. N. Rose (1897b) recognized five species of Brandegea (without a key to distinguish them). Of the five, B. minima (S. Watson) Rose was later transferred to Cyclanthera (D. M. Kearns and E. C. Jones 1992); the others have been relegated to synonymy of B. bigelovii.