In some localities, following moist winters, Desert-senna bursts into a riot of color in April and May adding a golden glory to the spring floral display. Representatives of the several desert species occur at elevations between 2,000 and 5,000 feet from Texas westward to southern California and south into Mexico. YELLOW [Illustration: Caesalpinia gilliesi] Common names: BIRD-OF-PARADISE-FLOWER Arizona desert: (_Caesalpinia gilliesi_). Yellow-and-red. May-August. Pea family. Size: Shrub, up to 10 feet tall. Widely grown as a decorative shrub by the people of Mexico, this spectacular import from South America is quite commonly used as an ornamental in yards and around houses in desert areas of the Southwest. Under suitable conditions, it may escape and grow wild. The very showy blossoms with yellow petals and long, thread-like, red filaments are certain to attract attention. In contrast to the striking showiness of the blossoms, the plant itself is straggling and unsymmetrical, and gives off an unpleasant odor. YELLOW [Illustration: Opuntia engelmanni Opuntia basilaris] Common names: PRICKLYPEAR, (_TUNA_), BEAVERTAIL Arizona desert: (_Opuntia engelmanni_). Yellow. April-June. California desert: (_Opuntia basilaris_). Magenta. March-April. Texas desert: (_Opuntia engelmanni_). Yellow. May-July. Cactus family. Size: Clumps, sometimes 5 feet high and 10 feet in diameter. The flattened pods, or stem joints, of the Pricklypears growing, as they do, in huge clumps make them the best known of the Cacti throughout the West. There are many species found throughout the United States, but the plants reach their greatest size and luxuriant growth in the desert areas of the Southwest. The large, red to purple and mahogany, juicy, pear-shaped fruits are known as _tunas_, and are eaten by many animals as well as by the native peoples. Flowers are large and spectacular. Although a number of species of Pricklypears are found in all of the desert areas, _O. engelmanni_ with its bright yellow flowers is the commonest form in both the Sonoran and Chihuahuan Deserts, while the Beavertail cactus with its magenta flowers and lack of large spines is the common and spectacular form of the Mohave Desert. Pricklypears are increasing in parts of the desert where conditions are favorable, especially where heavy grazing has given them an advantage over plants that are favorable to livestock. YELLOW [Illustration: Ferocactus wislizeni]