Flora of the Mojave Desert region

The flora of the Mojave Desert help define what is called the Mojave Desert in that the desert itself is generally considered to be outlined by the extent of growth of one of its plants, the Joshua Tree (Yucca brevifolia). Mojave Desert flora is not a vegetation type, although plants in the area have evolved in isolation because of physical barriers. This area includes southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona in the United States. The flora are adapted to extremely hot and dry conditions, but generally not as extreme as the adaptations needed for survival in the flora of the Sonoran Desert, which has an overlap in its major flora, such as the creosote bush (Larrea tridentata).

Physical conditions affecting flora

The Mojave Desert is diverse in topography, climates, and soil types, leading to a variety of recognized vegetation types. Flora within each vegetation type may overlap with other vegetation types, and with flora of the Sonoran Desert. Fine clays from erosion and decomposition of rocks, starting at the surrounding mountains, collect at the lowest areas. This is because the finer particles are more readily transported than the larger crystals, leading to dark colored clays at lower elevation, and lighter and more course grained sand crystals at higher elevations.

There are two periods with enough precipitation for general germination, winter-spring, and in late summer monsoons. Plants germinating in the late summer monsoons are less well studied.

The physical conditions in the Mojave Desert are widely varying. These conditions create recognized vegetation types, sometimes including Pinyon-juniper woodland, Joshua tree woodland, Sagebrush scrub, Blackbush scrub, creosote bush scrub, Saltbush scrub, Shadscale scrub, Desert dry wash, and lush Desert riparian.

Vegetation types

Alkali sink

The alkali sink vegetation type occurs below 2,000 feet (610 m), where rainwater drains to the lowest parts of the desert, and then collects because it is difficult to penetrate the caliche and clay under the surface. Water pools and evaporates, leaving behind dissolved salts and a very high pH. Plants adapted to such areas must therefore be salt tolerant, and are called halophytes (meaning "salt-loving").

Creosote bush scrub

Creosote bush scrub

Desert dune

Desert dune

Joshua tree woodland

Joshua tree woodland

Blackbush scrub

Blackbush scrub

Sagebrush scrub

Sagebrush scrub

Pinyon-juniper woodland

Pinyon-juniper woodland

Desert riparian

Desert riparian

Desert dry wash

Desert dry wash

Diversity and taxa

Trees

The Joshua tree Yucca brevifolia is a succulent yucca with a tree-like growth pattern. It outlines the extent of the Mojave Desert. The single-leaf pinyon pine Pinus monophylla grows 20 to 40 feet (6.1 to 12.2 m) and produces and edible pine-nut. The two leaf pinyon pine (Pinus edulis) grows in more eastern parts of the Mojave Desert, and also has edible nuts. The honey mesquites (Prosopis glanulosa and screwbean mesquite (Prosopis pubescens) are in the legume family (Fabaceae) produce edible beans that were a staple of Native Americans. The California juniper (Juniperus California) grows as a large shrub to shrubby tree with many branches from the base, whereas the Utah juniper (Juniperous osteosperma)is more treelike with a main trunk, and is found in the eastern part of the Mojave Desert. California fan palms require much water, and grow in dense stands in oases. Cottonwoods (Populus fremontii, Populus nigra) are trees in the willow family that require much water, and can be found near springs. The desert willow (Chilanthus linearis) requires much water, and has very deep roots so can grow in dry arroyos where water still flows under the ground. (not a true willow, but in the bigonia family, Bignoniaceae)grows as a large deciduous shrub to small tree, 10 to 30 feet (3.0 to 9.1 m) tall. Cat claw acacia (Senegalia gregii) is a shrub to small tree with claw-like thorns that grab into clothing holding back hikers, giving it the common name wait-a-minute bush. Various scrub oaks (Quercus spp.) grow as shrubs to small trees. Muller's oak (Quercus cornelius-mulleri) is shrubby to more tree-like, with some beautiful stands at skull rock in Joshua Tree National Park. Golden oak, or canyon live oak (Quercus chrysolepis), is a beefy-branched equivalent of the California live oak growing in more coastal areas.



The smoke tree (Psorothamnus spinosus) grows in dry arroyos and is shrub-like to growing as a small spiny, shrubby tree.

Willows grow as small shrubs to small trees, growing in or near springs and near rivers and arroyos with underground water closer to the surface, especially near springs, and include the coyote willow (Salix exigua, Gooding's willow (Salix goodingii), sand-bar willow (Salix exigua), red willow (Salix laevigata), and arroyo willow (Salix lasiolepis). Nonnative trees that have naturalized to the Mojave Desert include the tamarisk salt cedar or athel (Tamarix aphylla).

Cacti and succulents

Annuals

Annuals germinating in the winter-spring precipitation share affinities with flora of the Sonoran Desert.[1]:10

Aesthetics and unique specimens

References

  1. ↑ Sonoran Desert Wildflowers, Richard Spellenberg, 2nd ed., 2012, ISBN 9780762773688

Additional sources

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Further reading

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