Almost all types of cactus are native to North and South America, with a few found in the West Indies. There is only one type that doesn't grow in the Americas or West Indies, and that is the mistletoe cactus, which is found instead throughout tropical regions of the world including Africa, the Americas, Sri Lanka and Madagascar. The Tehuacán Valley in Mexico has the most varieties of indigenous cacti in the world.
There are about five different groups of cacti that are specific to their environments. Desert cactus favor lots of sun. Mountain species are extreme survivors that use a fur-like covering to keep from scorching during the day and freezing at night. Seashore cacti are challenging house plants because of their constant need for humidity and warmth. Those found in the rainforest will not conserve like their cousins, but are usually found on the forest floor and away from sunlight. Finally, savanna cacti are hearty plants that do well in lower temperatures, so long as it’s dry in the winter and hot in the summer.
Some types of desert cactus include prickly pears, saguaros, cholla jumping cactus, and barrel cactus. You may recognize saguaros. This tall species usually has one or more branches and can be seen in Arizona and sometimes in Western films. Cholla jumping cactus is also called teddy bear cactus because its branches resemble the chubby arms of a teddy bear. Don't be fooled — these are not cuddly teddies, and if you get too close they can easily lose their spines. The cholla spines may swell, which gives them the appearance of moving, to stick you. A pair of needle-nosed pliers may come in handy if you’re checking out this plant in its natural environment.
Mountain cacti like monk’s hood, bishop’s cap, or sand dollar cactus are often round in shape, as you might have guessed. Other types may take on a more column type shape. The cleistocactus has flowers that rarely open. The Greek root kleistos, where cleistoscactus get its name, means closed.
Seashore cactus such as melon and copiapoa are commonly sold in markets worldwide. You might recognize them as the little cactus balls covered in spines and planted in loose soil or small rocks. While these little plants are often difficult to grow, in the proper environment they can flourish.
Orchid cactus and the American winter favorite, Christmas cactus, are both types from the rainforest. Avoid setting these plants in direct sunlight as the sun can often burn their leaves. The flowers on this type, especially the Christmas cactus, can range from shades of yellow to red, including pinks and oranges. They are very beautiful and can brighten up any home in the middle of winter.
Savanna cacti such as Indian head, pincushion, snowball, or golden star are some of the easiest to grow. Mammillaria is the genus of one of the most popular, and has more than 171 different types of species. With proper care, they do very well in terrariums.