Cacti are dicots that have a fleshy, green, photosynthetic stem, the cladophyll, and leaves modified as spines. One group of cacti, Pereskia, has true leaves that are shed during long droughts. Some cacti are spineless and others have their spines modified as coarse hair. Most cacti produce perfect flowers. The flowers vary in size but are showy, usually delicate, and very attractive.
Most cacti are terrestrial but some are epiphytes.
Many cacti can be grafted and the grafts can be made across genera. Cephalocereus senilis is the old man cactus because it is covered in white, hair-like spines. Chamaecereus silvestr is the peanut cactus because of its clusters of short, spiny cylindrical branches. The genera Echinocactus , Notocactus , Rebutia and Lobivia are all called barrel cacti for their barrel-like shapes. Echinopsis multiplex is the Easter-lily cactus .