Opuntia robusta in length. Yellow, sessile flowers with a fleshy base are produced on the edges of the upper stem segments. These are followed by barrel-shaped fleshy fruits which are pink or purple and up to long. The species was first formally described in 1837 in "Enumeratio Diagnostica Cactearum hucusque Cognitarum". It has naturalised in the states of South Australia, New South Wales, Queensland and Victoria in Australia. Opuntia robusta Opuntia robusta, the wheel cactus, nopal tapon, or camuesa, is a species of cactus in the Cactaceae family. It is native and endemic to central and northern Mexico to within 100 miles
Opuntia fragilis in). Both the common and scientific names refer to the easily detached stem segments. This is known to be a means of plant dispersal. "Opuntia fragilis" is a small, prostrate plant, rarely more than 4 inches high: joints tumid, fragile, easily detached, oval, elliptical, or subglobose, 1-2 in. long and nearly as thick as broad, bright green: areoles ¼-½ in. apart, with whitish wool and a few white to yellow bristles, which are much longer and more abundant on older joints; spines 1-4, occasionally a few small additional ones, weak, dark brown, the upper one usually longer and stronger than