Yucca brevifolia Engelm
The Joshua tree, the largest of the yuccas, grows only in the Mojave Desert. Natural stands of this picturesque, spike-leafed evergreen grow nowhere else in the world. Its height varies from 15-40 feet with a diameter of 1-3 feet. They grow 2 to 3 inches a year, takes 50 to 60 years to mature and they can live 150 years.
Joshua trees (and most other yuccas) rely on the female pronuba Moth (Tegeticula) for pollination. No other animal visiting the blooms transfers the pollen from one flower to another. In fact, the female yucca moth has evolved special organs to collect and distribute the pollen onto the surface of the flower. She lays her eggs in the flowers' ovaries, and when the larvae hatch, they feed on the yucca seeds.
Without the moth's pollination, the Joshua tree could not reproduce, nor could the moth, whose larvae would have no seeds to eat. Although old Joshua trees can sprout new plants from their roots, only the seeds produced in pollinated flowers can scatter far enough to establish a new stand.
pioneers are said to have named this species "Joshua" tree because
it mimicked the Old Testament prophet Joshua waving them, with upraised arms,
on toward the promised land. This unique species grows abundantly at Joshua Tree National Park.
Joshua trees, Yucca brevifolia, grow in the Mojave Desert of southwest California, Nevada, Utah and Arizona, at elevations from 2,000 to 6,000 feet.
The Joshua tree likes dry soils on plains, slopes and mesas, often growing in groves.
The Joshua tree has bell-shaped blooms, 1.25 to 1.5 inches large, each with 6 creamy, yellow-green sepals, crowded into 12 to 18 inch, many-branched clusters with an unpleasant odor. The trees bloom mostly in the spring, although not all of them will flower annually.
The fruit is elliptical and green-brown. Six-celled, 2.5 to 4 inches, and somewhat fleshy, it dries and falls soon after maturity in late spring revealing many flat seeds.
|Rank||Scientific Name and Common Name|
|Kingdom||Plantae – Plants|
|Subkingdom||Tracheobionta – Vascular plants|
|Superdivision||Spermatophyta – Seed plants|
|Division||Magnoliophyta – Flowering plants|
|Class||Liliopsida – Monocotyledons|
|Family||Agavaceae – Century-plant family|
|Genus||Yucca L. – yucca|
|Species||Yucca brevifolia Engelm. – Joshua tree|
Want to grow your own Joshua tree?
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