Explanation:
Euphorbia, colocasia and Bougainvillea grow in well drained soil but opuntia grows in arid regions which have little or no rain, like in xerophytic conditions. In these circumstance, the leaves are changed to resemble spines in order to minimize water loss through transpiration. On the other hand, the stem chang and undergo photosynthesis, becoming green and flattened. Phylloclade is a term for such stem alteration.
