Cactus exhibit strange shapes, spines, and showy flowers. Today, they are found around the world. All but four varieties are native to the Americas. Like all living things, cactuses vary greatly. Some cactuses look like pincushions. Others resemble starfish or even blades of grass. There are about 2,000 different species of cactuses. Every cactus of a given species does not look exactly alike. For example, spines may vary in length and color.
Cactus spines keep the plant from being eaten by most animals. Cactus spines can be short, long, soft or sharp. Spines can be straight or hooked.
Spines grow on the stem in clusters called areoles. The areoles sometimes form patterns along the cactus. Look for the ridges in the barrel cactus above. The ribs give the plant shade and help store water.