Stem photosynthesis

Cactus CU

All cacti are succulents, but not all succulents are cacti—at least that was what I was taught for decades, although I find whispers on the Internet that this is no longer considered a truth. Cacti are New World—except one species in southern Africa. Cacti have spines not thorns (modified leaves vs modified branches). The strange growths and textures of the cacti exterior help it conserve water in part by trapping an air layer that reduces air movement and helps the plant retain water.