Cactus Family
Grizzly Bear Cactus, Opuntia trichophora, BRITTON AND ROSE
Flowers are 3 inches or more across, usually light-yellow with fine sheen, several of them erupting from the edge of a flat, oval joint. Plant spreads over a circular area, about 2 feet in diameter, and is made up of numerous connected flat joints, of light-green color, all heavily armored with pale, sharp spines, some of which, in old plants, may be flexible and hair-like. Grows on clay soil in foothills and plains of middle and western Colorado. Blooms June-early July.
Several species of Opuntia closely resemble each other. Some of them, including a few found in Colorado, bear soft, juicy fruits which are quite good eating when the prickles on the skins are removed, so all of them are called prickly pear. The one shown above grows freely on the high grassy flats of the San Luis Valley. It bears dry, hard fruits, as do most of our Colorado species. The prickly pears, like all the other cacti, accumulate moisture, when they get a chance, in the soft pulp of their round or jointed stems. Then, over periods of drought, this moisture is used to produce flowers, to mature seeds and to keep the plant alive. The whole plant shrinks visibly if the times between drinks are long. But for the defensive armor of their spines, few of them would survive, because in a thirsty land every hungry cow is looking for moisture too.
Evening Primrose Family
Yellow Evening Primrose, Oenothera brachycarpa, GRAY
Flowers are cadmium-yellow, fading old-rose, 2½ inches across, of 4 wide petals. The 4 narrow sepals bend back and at their base merge into a hollow tubular stem. The style branches at its tip into 4 conspicuous slender stigmas. Plant has little or no main stem; leaves are dark-green, strap-shaped, 3 inches long. Grows in foothills, but only where soil is somewhat marly. Blooms May-June.
Look for this one of our numerous evening-primroses about Memorial Day. Soil formed from the disintegration of Niobrara shale such as we find along the Hogsback near Denver, or along the Boulder-Lyons road, is its preference. The plants are rather ragged, but the flowers draw all our attention to their soft, clear yellow as they spread open in the sunshine. They last but a day—fading into soft rosy colors. The white members of this family are much better known. Several such species common on the plains are so responsive to early summer rain that within days after a good shower all our roadsides and even vacant lots will be gay with their short-lived beauty.
Evening Primrose Family
Fireweed, Epilobium angustifolium, L.
