Vines sprawling, trailing, or climbing over associated plants, often completely covering them, stems to 2(–4) m. Leaves: petiole 8–25 mm; blade 1.5–5(–7) cm, base cordate to convex, lobes broader and shallower on juvenile growth, narrower (to linear-oblong) on distal stems, abaxial surface glabrous, adaxial surface and margins pustulate-scabrous to pustulate-hirsutulous. Staminate inflorescences 2–4 cm. Capsules 0.5–1.2 cm, beak (3–)4–7 mm. Seeds 4–5 mm.
Phenology: Flowering (Feb–)Mar–Apr(–later sporadically).
Habitat: Desert wash bottoms and banks, cliffs, canyons, moist areas from tank seeps, roadsides, Larrea flats, Sonoran desert scrub, upland Sonoran desert scrub, desert riparian zones, commonly with Acacia, Ambrosia, Atriplex, Cercidium, Larrea, Lycium, Olneya, Parkinsonia, Prosopis
Elevation: 20–600(–800) m
Ariz., Calif., Mexico (Baja California, Baja California Sur, Sonora).
Plants of Brandegea bigelovii are cultivated for the beauty of their clusters of white staminate flowers. Garden plants in Tucson flower from February through the summer, except during extreme heat. According to R. S. Felger (2000), B. bigelovii is the most common and widespread vining plant in northwestern Sonora.