Modifications of leaf

Opuntia is a xerophyte; its leaves are modified into spines to reduce transpiration.

In Australian Acacia the leaves are small and short-lived; the petiole expands, becomes green and synthesises food. Such a petiole is called a phyllode.
Opuntia and Euphorbia have flattened or fleshy photosynthetic stems (phylloclades), and Asparagus has cladodes.