Yucca brevifolia

 Yucca brevifolia (Joshua tree) ( )

Asparagaceae

  • Joshua tree is a true arboreal species that commonly attains a height of 30 ft or more, with some individuals larger with massive, branched crowns. The species occurs widely in a ring of higher elevation stands of creosote bush scrub around the Mojave Desert, although present at elevations above 6, 000  ft in the southern Inyo Range to the north of Death Valley. Two varieties of Joshua tree are recognized by botanists. The variety brevifolia is distributed in the western and northern Mojave Desert from north of Death Valley south to Joshua Tree National Park, with a western limit of distribution in the Techachapi Mountains near Tejon Pass. It is taller, branches higher on the trunk, and has longer leaves than the variety jageriana which is distributed in the northeastern Mojave Desert from the Mojave National Preserve eastward into Nevada and northern Arizona. Joshua trees are slow growing, typically adding only a few inches of height annually. Joshua tees are slow growing, typically adding only a few inches of height annually. Older dead leaves retain their stiffness and are bent downward, playing a role in preventing rodents from climbing up the stems and feeding on the fruits. From March-May dense clusters of cream-colored flowers are produced at the branch tips. The Joshua tree seeds are spongy rather than fleshy as in other yucca species-suggesting that this species forms its own distinct group within the genus. Although there is no absolute means of aging Joshua trees because, as monocots, they lack tree rings, it has been suggested that typical life spans are 150 years and that larger individuals may live to 300 years. Some suggest that the largest Joshua trees may reach an 1,000 years, which is highly speculative at best. "California Desert Plants, Philip W Rundel, Robert J Gustaffson, Michael E Kauffmann."
  • The name Joshua tree came from early Mormon settlers. "Arizona Highways Presents Desert Wildflowers 1988" 
  • The tall, shaggy-barked Joshua-tree produces gangly clusters of leaves that are wide-ridged and have a coarse-toothed edge. Short flower stalks arise from the ends if its leafy branches. Forests of these plants are best known north and west of Wickenburg, on rocky plains and hillsides. The plant's short bloom time is seldom more than three weeks, but the simultaneous bloom of so many large, pale green flowers lights up the desert in March and April. The yucca moth gathers pollen, crams it on the stigma, and then lays its eggs in the developing fruit. "Arizona Highways Presents Desert Wildflowers, 1988"
  • Seeds in flats for transplanting/Treat seeds with fungicide and place atop cactus mix soil, then cover lightly with coarse gravel, and keep moist/Time of planting: spring-summer. "Arizona Highways Presents Desert Wildflowers, 1988".
  • California desert. Green-white. February-April. Lily Family. Size: 15 to 35 feet high; spread of 20 feet. Because the presence of this tree yucca marks more effectively than any other plant, the limits and extent of the Mojave Desert, this species is worthy of special recognition. It holds, in the Mojave 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 Mojave 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 gas 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, woodrats, and several species of insects are closely associated with this plant, 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 Josua. "Flowers of the Southwest Deserts. Natt N. Lodge". 

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