Frequently the automobile traveler’s attention is arrested by a pale yellowish blotch in the green of the roadside vegetation. Examination shows this to be caused by the matted yellowish stems and the white to pale yellow, fleshy blossoms. These flowers are attractive and often abundant enough to make a showy display. Dodder is found widespread throughout the United States and is often a serious parasitic pest on crops of economic importance. Desert species are usually found infesting Mesquite, Goldenrod, Aster, Burrobush, Seepwillow, and Arrowweed. Although certain Dodders show a preference in choosing hosts (_C. denticulata_ common on Creosotebush), most of them grow readily upon various plants. WHITE [Illustration: Yucca brevifolia] Common Names: JOSHUA-TREE, TREE YUCCA, GIANT JOSHUA California desert. (_Yucca brevifolia_). Green-white. February-April. Lily family. Size: 15 to 35 feet high; spread of 20 feet. Because the presence of the grotesque Joshua-tree marks, more effectively than any other plant, the limits and extent of the Mohave Desert, this species is worthy of special recognition. This tree Yucca holds, in the Mohave Desert, similar status to the Saguaro in the Sonoran Desert. Strangely enough, in west-central Arizona, the Saguaro and Joshua-tree are found growing together and there the Sonoran and Mohave Deserts overlap. And, just as in southern Arizona an area has been set aside as Saguaro National Monument to preserve and protect that species, so in southern California we find the Joshua Tree National Monument. The Joshua-tree is outstanding among the many species of Yucca because of its short leaves growing in dense bunches or clusters, and because the plant has a definite trunk with numerous branches forming a crown. Great forests of these sturdy trees are found in parts of southern California, southern Nevada, southwestern Utah, and northwestern Arizona where rainfall averages 8 to 10 inches per year. Flowers of this Yucca develop as tight clusters of greenish-white buds at the ends of the branches, but do not open wide as do the flowers of other Yuccas. Joshua-trees do not bloom every year, the interval apparently being determined by rainfall and temperature. Birds, a small lizard, wood rats, and several species of insects are closely associated with the Joshua-tree, making use of it for food, shelter, or nest-building materials. Indians use the smallest roots, which are red, for patterns in their baskets. The name “Joshua-tree” was given by the Mormons because the tree seemed to be lifting its arms in supplication as did the Biblical Joshua. WHITE [Illustration: Yucca torreyi Yucca schidigera Yucca arizonica]