Cacti do not have leaves. The leaves have been replaced by spines.
Most of their stomata are on the underside of the leaf.
Cactus have a waxy layer on them to prevent water loss and reduce transpiration
cuticle is the thick layer outside the leaf to prevent loss of water.
prevent water loss
xylem
To prevent water loss
The two structures in plant leaves that prevent the loss of water are stomata (located in the bottom part of the leaf) and the epidermis (covers the top and bottom of the leaf).
The roots grow deeper to gather more water, the stems are woody and the leaves are waxy to prevent water loss by transpiration, cacti have also evolved other mechanisms to prevent water loss by transpiration.
A layer of the leaf called the cuticle cuts down on water lost by evaporation. Also, the guard cells around the stomata which can close to prevent water loss.
A cactus is deeply rooted and, even in a hot desert, there may be dampness below. Also, whenever it does rain, the cactus will store water in special cells that cause the cactus to swell. Another adaptation is that a cactus's covering is waxy to prevent water loss. While it may be hot during the day, temperatures can plummet at night.
cuticle it on the leaf for the bugs to eat to keep out posion
the underside of the leaf loses water much faster