The cactus family is one of the most common in house plant collections. There are many members of the family and they are well adapted to indoor culture. 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.