Opuntia Mill.
Prostrate to arborescent shrubs. Stems jointed, the segments cylindric to globose or flattened and pad-like. Areoles bearing numerous glochids and often hairs and spines. Lvs small, subulate or terete, caducous. Fls single in an areole, usually on margins of stem segments. Sepals green, or inner sepals similarly coloured to petals. Petals green, yellow, red, or occasionally white, opening widely. Stamens much < petals. Ovary with areoles and glochids, often with spines. Berry rather dry to very juicy, sometimes spiny. Seeds with whitish bony aril.
Key
1
Stem segments flattened, ± ovate to oblong or obovate; petals 3-4 cm long, yellow except on outside of outer petals
250-300 spp., from Canada to Patagonia. Naturalised spp. 2.
