29.
Opuntia basilaris
Engelmann & J. M. Bigelow, Proc. Amer. Acad. Arts. 3: 298. 1856.
Beavertail pricklypear
Shrubs
, forming clumps, 1-2(-3) segments tall, to 7-40 cm.
Stem segments
not disarticulating, blue- to yellow-green, sometimes tinged maroon-purple, flattened, spat-ulate to broadly obovate or subcircular, thick, 5-22(-35) × 2-13.5(-16) cm, nearly smooth, papillose to puberulent (rarely glabrous); areoles 4-16(-19) per diagonal row across midstem segment, circular to elliptic, 3-5 × 3 mm; wool white to tan, aging gray.
Spines
0(-8) per areole, when present, usually in distal areoles, spreading, yellow, straight, acicular, 5-25 mm.
Glochids
numerous, nearly filling areoles, yellow to red-brown or dark brown, to 3 mm.
Flowers:
inner tepals pink to magenta throughout (rarely white), 25-40 mm; filaments red-magenta (rarely pale); anthers yellowish; style white to pink; stigma lobes white to cream.
Fruits
maturing tan, 20-40 × 15-23 mm, dry at maturity, puberulent, spineless (except in var.
treleasei
); umbilicus 5-12 mm deep; areoles 24-76.
Seeds
yellowish to tan, ± subspheric but angular, thick, 6.5-9 × 6.5-7 mm, sides smooth or bearing 1-3 depressions; girdle protruding to 1 mm.
Varieties 4 (4 in the flora): sw United States, n Mexico.
