The first image that comes to mind when the word cactus is mentioned is a blazing desert, a barren landscape stretching into the horizon, but cacti actually grow all over the world. Some areas include rainforests, where the climate is wet and humid, and even areas that experience harsh winters. In general, cacti that are used to very arid conditions are spiny, rounded plants. The types of cactus that grow and thrive in rainforest environments grow in the crook of trees and do not have spines. The difference in their appearances is a result of the different needs they have in their particular environments.
If planting cacti, be sure to know the climate to which they are accustomed. Some cacti, if not well adapted to heat, will burn under the sun if not protected well enough. When using as landscape plants, place in a location that receives some shade. This is especially true for cacti that are planted in pots because they become warmer than they would if planted in the ground. If yellow and brown spots develop on your cactus, it is likely because it is receiving too much sun through the day.
The cactus is a succulent, which means a plant that stores water to get it through times of drought. Many plants do this, such as daisies and lilies. Characteristics that separate the cactus from these other types of plants are the structure of their flowers as well as structures called areoles. An areole is the spot where new growth, spines, flowers, or hairs grow. It resembles a small felty grey pad. If a plant has spines but does not have areoles, it is not a cactus.
Cacti can add a very unique element to your home and garden, but it is important to do your research before purchasing or planting so that neither your garden nor your plant will suffer in the end.