Cacti are native to the Americas and come in dozens of varieties. Most are easily grown as houseplants in south-facing windows. Move them outdoors during summer, but put them in an area protected from natural rainfall; cacti will turn to mush and rot if they receive too much water. Many cacti are native to high desserts in mountain plateaus and are much more hardy than their desert origins suggest.
Golden Barrel Cactus
Golden barrel cactus (Echinocactus Grusonii) is a barrel-shaped cactus with a green body and yellow-gold spines. Its body stretches upward as it matures, becoming more barrel shaped as it ages. It bears golden flowers in summer at the top of the plant. A good cactus for a beginner to grow indoors.
Giant Saguaro Cactus
Giant saguaro (Carnegeia gigantea) is the classic cactus with a large, thick trunk and outstretched branches that resemble arms. This is the same cactus that is often associated with the American Southwest, seen in films and television shows set in the wild west. It bears white flowers in spring. Although it will eventually grow too large for a container, it will happily grow indoors for many years before that happens.
Column cactus (Cereus uruguayanus) are often called night-blooming cereus. Their white flowers bloom at night, with their outer petals taking different, pastel colors. Column cactus are a blue-green color with brown spines. They are an excellent choice for growing indoors and fare well when grown outdoors in frost-free weather. They will grow to a height of 3 to 6 feet.