All cactus plants are members of the Cactaceae family, and there are thousands of species of cactus. There are two large groups of cacti grown as houseplants; both are popular and familiar, and both can thrive indoors with relatively little maintenance.The desert cacti are the more "traditional" cacti, usually covered with spines or hair and often growing in paddles, balls, or obelisks. Forest cacti grow in wooded areas, ranging from temperate forests to subtropical and tropical regions. The most well-known forest cacti may be the Christmas cactus. Both desert and forest cacti boast beautiful blooms, but they have very different growing habits.