A succulent is a plant that stores water in its leaves or stems (or occasionally in its roots). All cacti are succulents, but not all succulents are cacti.
These are leafless, spiny, hardy desert plants with large, colorful flowers. They range in height from a few inches to 40 feet or more tall. Cacti have relatively large fruit with many seeds. Fruit is produced mainly in spring and summer, but some remain on plants into winter. Many are relished by fruit- and seed-eating animals. Cactus flowers offer nectar for bats and hummingbirds, while insects on flowers attract birds.