Regularity: Regularly occurring
Mojave Desert Habitat
This taxon is found in the Mojave Desert, the smallest of the four North American deserts. While the Mojave lies between the Great Basin Shrub Steppe and the Sonoran Desert, its fauna is more closely allied with the lower Colorado division of the Sonoran Desert. Dominant plants of the Mojave include Creosote Bush (Larrea tridentata), Many-fruit Saltbush (Atriplex polycarpa), Brittlebush (Encelia farinosa), Desert Holly (Atriplex hymenelytra), White Burrobush (Hymenoclea salsola), and Joshua Tree (Yucca brevifolia), the most notable endemic species in the region.
The Mojave’s warm temperate climate defines it as a distinct ecoregion. Mojave indicator species include Spiny Menodora (Menodora spinescens), Desert Senna (Cassia armata), Mojave Indigobush (Psorothamnus arborescens), and Shockley's Goldenhead (Acamptopappus shockleyi). The Mojave supports numerous species of cacti, including several endemics, such as Silver Cholla (Opuntia echinocarpa), Mojave Prickly Pear (O. erinacea), Beavertail Cactus (O. basilaris), and Cotton-top Cactus (Echinocactus polycephalus).
While the Mojave Desert is not so biologically distinct as the other desert ecoregions, distinctive endemic communities occur throughout. For example, the Kelso Dunes in the Mojave National Preserve harbor seven species of endemic insects, including the Kelso Dunes Jerusalem Cricket (Ammopelmatus kelsoensis) and the Kelso Dunes Shieldback Katydid (Eremopedes kelsoensis). The Mojave Fringe-toed Lizard (Uma Scoparia), while not endemic to the dunes, is rare elsewhere. Flowering plants also attract butterflies such as the Mojave Sooty-wing (Pholisora libya), and the widely distributed Painted Lady (Vanessa cardui).
There are a total of eight amphibian species present in the Mojave Desert all of which are anuran species: the endemic Relict Leopard Frog (Lithobates onca); the endemic Amargosa Toad (Anaxyrus nelsoni); Lowland Leopard Frog (Lithobates yavapaiensis); Red-spotted Toad (Anaxyrus punctatus); Southwestern Toad (Anaxyrus microscaphus); Great Basin Spadefoot (Spea intermontana); Great Plains Toad (Anaxyrus cognatus); and the Pacific Treefrog (Pseudacris regilla).
The native range of California’s threatened Desert Tortoise (Gopherus agassizii) includes the Mojave and Colorado Deserts. The Desert Tortoise has adapted for arid habitats by storing up to a liter of water in its urinary bladder. The following reptilian fauna are characteristic of the Mojave region in particular: Gila Monster (Heloderma suspectum NT); Western Banded Gecko (Coleonyx variegatus), Northern Desert Iguana (Dipsosaurus dorsalis), Western Chuckwalla (Sauromalus obesus), and regal horned lizard (Phrynosoma solare). Snake species include the Desert Rosy Boa (Charina trivirgata gracia), Mojave Patchnose Snake (Salvadora hexalepis mojavensis), and Mojave Rattlesnake (Crotalus scutulatus).
Endemic mammals of the ecoregion include the Mojave Ground Squirrel (Spermophilus mohavensis) and Amargosa Vole (Microtus californicus scirpensis); and the California Leaf-nosed Bat (Macrotus californicus).
- C. Michael Hogan & World Wildlife Fund. 2013."Mojave Desert". Encyclopedia of Earth, National Council for Science and the Environment, Washington DC ed.Mark McGinley.
- Michael G. Barbour and William Dwight Billings. 2000. North American Terrestrial Vegetation. Cambridge University Press. ISBN 0-521-55986-3.
Life History and Behavior
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Atriplex hymenelytra, or desert holly, is silvery-whitish-gray shrub in the goosefoot family (Chenopodiaceae), native to southwestern United States deserts.:141:271 It is the most drought tolerant saltbush in North America. It can tolerate the hottest and driest sites in Death Valley, and remains active most of the year.
The common name refers to the leaves that are shaped similar to holly, but the plants are not related.:141 The toothed leaves and the small reddish fruits borne on the plant give it a passing resemblance to the unrelated European holly.
Range and habitat
Desert holly grows in alkaline locations such as desert dry wash and creosote bush scrub in the Mojave Desert and Sonoran Desert down to Baja California. In the Sonoran Desert it grow in northwestern Mexico, western Arizona, and southeastern California to southwestern Utah, and can be found at elevations ranging from 250 to 3,900 feet (76 to 1,189 m).:141
With dry soil, it can survive temperatures as low as −10 °F (−23 °C), dies if the ground freezes.
Atriplex hymenelytra is generally a compact, rounded bush, 8 to 48 inches (20 to 122 cm) tall, covered in distinctive reflective silver-gray, twisted, oblong, many-pointed leaves.:141 It drops its leaves drought deciduous in extreme drought conditions.
It tolerates alkaline soil, salt and sand. The leaves accumulate salts which helps extract water from the soil when other plants cannot. Salt is shed by dropping the leaves. It can live in up to 30 ppm Boron in solution, compared to most plants which can tolerate only about 1-5 ppm. As with other desert climate members of the Atriplex genus, it uses water conserving C4 photosynthetis, and it removes salts by having bladders in the leaves that keep the salt from the plant cells.
Roots, stems, and leaves
Oval to round, 1⁄4 to 3⁄8 inch (0.64 to 0.95 cm), silvery-gray leaves have a whitish reflective coating of tiny gray to white scales, and are shaped like twisted or wavy holly leaves, with toothed margins.:141 The silvery color is from salts that collect on surface hairs.Template:Dubious as to only cause of coloration This helps reflect the light and therefore reduce the amount of water lost.
Inflorescence and fruit
It blooms from January to April in the Sonoran Desert.:141
Female flowers are green.:141
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- Wildflowers of the Sonoran Desert, Richard Spellenberg, 2nf ed, 2012, ISBN 9780762773688
- Mojave Desert Wildflowers, Pam Mackay, 2nd ed.
- http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?3084,3089,3112 Jepson
- Atriplex hymenelytra, Las Pilitas Nursery
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