
Yucca brevifolia
Range:
The deserts of extreme
southwest California, Nevada, Utah and Arizona, at elevations
from 2,000 to 6,000 feet.Habitat: Dry soils on
plains, slopes and mesas, often growing in groves.
Flowers:
Bell-shaped, 1.25 to 1.5 inches with 6 creamy, yellow-green
sepals. Crowded into 12 to 18 inch, many-branched clusters with
an unpleasant odor, mostly in the spring. Not all trees flower
annually.
Fruit: Elliptical green-brown, 6-celled,
2.5 to 4 inches, somewhat fleshy. Dries and falls soon after
maturity in late spring revealing many flat seeds.
Description: The Joshua Tree, the largest of the
yuccas, grows only in the deserts of the Southwest. Natural stands of
this picturesque, spike-leaved evergreen grow nowhere else in the
world. Its height varies from 15 to 40 feet with a diameter of 1 to 3
feet.
Originally thought to be members of the
Agave (Century Plant) Family, the Joshua Tree and other yuccas have been
reclassified as members of the Lily (Liliaceae) Family. Two
variations of the Joshua Tree are classified as J. brevifolia
var. herbertii and
J. brevifolia var. jaegeriana
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
then 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 an old Joshua Trees can sprout new plants from
its 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.

It is indeed a beautiful sight outlined against the
mountains and the sky