Most Front Range hikers will recognize the prickly pear cactus and ball cactus, though some erroneously call the latter a barrel cactus. What many don’t realize is that this area has quite a few different cactus species – five prickly pears alone, though two of those live on the plains, only coming to the very edge of the montane.
Cactus are adapted for dry environments. Most lack leaves, and those that have them generally hold them only briefly in the spring. The stem of the cactus is usually swollen and large, and constitutes the bulk of the plant. Sometimes the stems are called pads, as with the prickly pear cactus. Since there are few to no leaves, the stems carry out photosynthesis. Cactus famously sport sharp spines, which are modified leaves or buds. Several species also have glochids, which are very small, hair-like spines. If you accidentally brush a cactus you can spend hours looking for the glochids embedded in your skin, often fruitlessly – they can be so minute that you can feel them but not see them. Spines grow in clusters from specialized branches on the stem called an areole. Areoles come in many shapes and sizes and among plants are unique only to cacti. Flowers also grow from areoles. The pads often shrink in the winter, but expand again in the spring as they collect new moisture. Most species of cactus along the Front Range bloom in late April and through May, and some into June. The flowers close when it is dark or cloudy, so look for the flowers midday when the weather is bright and sunny.
Cactus from three different genera are common in the foothills of the Front Range. The first, and most distinguishable, is the prickly pear cactus, of the genus Opuntia. These are identified by the rounded or pear-shaped flattened pads. Pads on some species can be as large as your hand. The most common that you will see in the montane zone is the plains prickly pear (Opuntia polyacantha). The pads grow up to five or six inches long. Look close – but don’t touch! – at the spines and the areoles. All of the prickly pear species have many small glochids. In the Front Range, they are the only cactus that has them. In mid-spring, look for flowers ranging from yellow to pink. Another prickly pear species is Opuntia macrorhiza, which looks very similar to the plains prickly pear, except the flowers are only yellow and the joints between pad segments have few, if any spines, whereas the joints on plains prickly pear have many.
There are several less-common species of prickly pear in the area. One is the brittle cactus (Opuntia fragilis). The pads on this cactus are much smaller, only half the size of the plains prickly pear. The segments of this cactus are easily broken off, hence the common name. The flowers are almost universally yellow, but an individual may not bloom every year.
The second common genus is Echinocereus, also known as the hedgehog cactus. One common hedgehog cactus is also called hen-and-chickens (Echinocereus viridiflorus). These cacti are egg-shaped, growing several inches upwards from the ground. They grow in grassy areas, more common in the plains but sometimes found in the lower reaches of the montane. Their flowers are yellow, and sometimes green-ish.
The third common genus is Pediocactus, also known as ball cactus. This rounded cactus grows a few inches high. The flowers are purple, with many pointed petals. Ball cactus bloom later than most cactus species in the area, usually in May and June. Some claim that the flowers have a strong rose fragrance, but others have not been able to smell this. These are common in the foothills, so if you see a ball-shaped cactus in the mountains, more than likely it is a ball cactus as opposed to a hen-and-chickens.
A fourth genus, Coryphantha, sometimes called Escobaria, or nipple cactus, are rare in the foothills but common on the plains. These small ball-like cactus are usually covered with many spines. To tell the difference between these and the ball cactus, look at the tubercles – the nipple or wart-like projections on the main stem. On the nipple cactus the tubercles have grooves on the upper sides, which are lacking on the ball cactus. You are not likely to see nipple cactus along trails in the Front Range foothills.
With proper preparation, most cactus in the area are edible, and some are tasty. The preparation, however, can be tedious with the additional risk of getting stabbed by the spines, so collecting them for food is not worth it, not to mention that these plants shouldn’t be picked in the wild to begin with. If you want to try it, some ethnic grocery stores sell prepared cactus.
Unfortunately many local cactus species have fallen victim to collection for sale and use in gardens. Local ball and hedgehog cactus have especially been impacted. If you find some of these special plants, please enjoy them in place and leave them be.