Colorado Cactus
We do have cacti in Colorado and they even grow in the mountains. The most obvious and plentiful cactus in Colorado is the Prickly Pear (Opuntia polyacantha). If you spend any time walking around the drier areas of the state up to 8000-9000 feet elevation, you may have the unfortunate experience of running into one. The spines of Prickly Pear are vicious (polyacantha means "many spines"), but its flowers are magnificent, either in yellow or magenta.
These photos were taken on the Pawnee National Grasslands, following a wet spring when blossoms were plentiful. Prickly Pear spreads easily from stem segments that are broken off and scattered, usually by animals. While Prickly Pear can tolerate cold temperatures, it rots when it absorbs too much water. The red fruit of Prickly Pear cactus is often cooked and made into jelly or syrup. In fact, every part of Opuntia is edible (once you get rid of the spines) and has long been used as a food source by native people in Southwestern United States and Mexico. There are many species of Opuntia. One of my favorites is native to the Sonoran desert and has stems that are purple in color with yellow blossoms. This Santa Rita Prickly Pear is a favorite for landscaping in desert areas.
Another cactus that grows in Colorado is the Hedgehog cactus (genus Echinocereus). It is less common, but I have found it on rocky hillsides north of Fort Collins. The name Hedgehog is derived from the Greek word echino which means (guess what?) hedgehog. This is one of those cases where the scientific classification is evolving or, at least, confusing for I have seen hedgehog cactus listed under three different genuses (Pediocactus, Echinocactus, and Echinocereus) I'm not capable of sorting it out, but hedgehog seems quite appropriate for this spiny little rascal. The thorns are often so thick that the cactus looks white on top. It does have lovely flowers, too, but I haven't been lucky enough to see them yet. Maybe this year....
Undoubtedly, my favorite is this little Mountain Ball Cactus, photographed in Rocky Mountain National Park at about 9000 feet elevation. Its scientific name is Pediocactus simpsonii. Pediocactus, ironically, means "cactus of the plains" (because the first plants were found on the plains). These are fascinating little plants and are considered rare. They are found in small populations scattered over several western states. They can survive temperature variations from hot summers to icy winters because they can draw themselves below the earth for protection, then emerge in spring and autumn when temperatures are milder. They also take on color that almost matches the soil in which they grow. Since they are so small (the plant in the photo was only 6-8 inches in diameter) and retiring, it is often impossible to find them unless they are blooming. I didn't realize how lucky I was when I discovered these plants. Since then, I have searched for them during the summer in this location, with no success.
One species of Pediocactus is officially listed as endangered. Pediocactus knowltonii grows on only one hillside on the Colorado/New Mexico border. Knowlton's cactus is only one inch high and one inch in diameter. Its white blossoms exceed the size of the plant. This is the smallest population of any cactus in the United States, and it was nearly wiped out by collectors who dug up many of them. The Nature Conservancy now owns the land and protects this site, so the cactus has increased in numbers, but the area is well known to collectors and it is still endangered. Efforts to colonize other sites have not been successful so far.
Cacti survive in hot, dry climates because they have adapted to store every speck of moisture available. Cacti have no leaves; photosynthesis (converting sunlight to energy) is accomplished by the green stems, that can expand to store water. With no leaves to transpire, the plant does not lose water during the day as other plants do. Spines protect the cactus from animals and also may collect dew that drops to the ground around the plant where it can be absorbed by the roots. Some cacti have so many white spines that they reflect heat and shade the stems. While those big, showy blossoms are beautiful, they are really designed to attract the desert birds and insects needed to pollinate the plants. Some cacti bloom at night when it is cooler, and certain moths are attracted to the blossoms.
Cacti and other succulents are an amazing group of plants that fascinate me a little more every time I bring them into my awareness. I'm recommending a couple of books for those who would like to know more about cacti.
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