Joshua Tree

Yucca brevifolia Engelm

Joshua Tree

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.

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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.

Mormon 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.

Range

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.

Joshua Tree


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Habitat

The Joshua tree likes dry soils on plains, slopes and mesas, often growing in groves.

 

 

Flowers

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.

Joshua Tree

 

Fruit

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.

Joshua Tree

Rank Scientific Name and Common Name
Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Liliopsida – Monocotyledons
Subclass Liliidae
Order Liliales
Family Agavaceae – Century-plant family
Genus Yucca L. – yucca
Species Yucca brevifolia Engelm. – Joshua tree

 



Click here to read more about the yucca moth.

Want to grow your own Joshua tree?

More...

Desert Plant & Wildflower Index
Joshua Tree National Park
Mojave Yucca
Plants And Animals How They Are Classified
U2′s Joshua Tree

 

Photos tips: Most digital point-and-shoot cameras have a macro function - usually symbolized by the icon of a little flower. When you turn on that function, you allow your camera to get closer to the subject, looking into a flower for example. Or getting up close and personal with a bug. More on desert photography.

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What's Blooming Now - Check the Wildflower Reports

 

 
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