Opuntia robusta

A shrubby or tree-like cactus, to 2m tall in its native Mexico, with stems composed of thick, flat, rounded, greyish or bluish segments to 40cm across. 2-12 spines arise from each areole. Mature plants produce shallowly bowl-shaped, yellow flowers to 7cm across in summer, followed by spherical, red fruits; but neither flowers nor fruit are likely to be produced in the UK