Amazing Adaptations of Utah’s Desert Plants

Amazing Adaptations of Utah’s Desert Plants: Click to view larger image of Tap roots that grow deep into the soil to reach groundwater, Photo Courtesy and Copyright Mark Larese-Casanova, Photographer
Tap roots grow deep
to seek groundwater
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Winterfat trichomes
Hair-like trichomes provide shade
and absorb dew
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Prickly Pear Cactus
Fibrous roots quickly absorb water
and store it in wide succulent leaves
Photo Courtesy US FWS
Gary M. Stolz, Photographer

Waxy Creosote Bush
Leaf coating inhibits desication
Photo Courtesy & Copyright
Mark Larese-Casanova, Photographer

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Anyone who lives in Utah knows that it’s a dry state. In fact, around three-quarters of our state is considered desert. A desert is often characterized as an area that receives less than ten inches of precipitation each year. But, high levels of evaporation, which are influenced by temperature, wind speed, and solar radiation, also contribute to creating a dry desert ecosystem.

So, how exactly are plants able to survive in Utah’s deserts, which are so dry? It turns out that the plants that grow and flourish in Utah’s deserts have an amazing array of adaptations for survival.

Many shrubs and trees, such as desert willow, and certain species of sagebrush and mesquite, have thick taproots that grow deep into the soil to reach groundwater. This helps the plants survive the hot, dry summer. Some mesquite taproots have been found to grow as deep as 200 feet to reach a constant water supply.

Cacti, such as the various types of prickly pear, have almost an opposite adaptation. They produce dense tufts of fibrous roots just below the surface of the soil. This allows cacti to quickly absorb water from brief rainstorms, and then store the water in their thick, succulent leaves.

As temperature increases, desert plants face the danger of excessive water loss from their leaves. A thick, waxy coating on the outside of leaves often helps to retain water. The shiny wax also reflects sunlight to keep the leaves relatively cooler. To further reduce leaf temperature and water loss, some plants, such as brittlebush, grow light-colored dense ‘hairs’ on their leaves and stems. These trichomes not only shade the plant, but also aid in absorbing water from morning dew.

If temperatures get too hot, and drought stress too great, some plants, such as creosote bush and ocotillo, may drop their leaves several times each year to ensure survival. Some of these plants have green chlorophyll in their stems so they can still produce food through photosynthesis when there are no leaves on the plant.

While this is just a sample of an amazing collection of adaptations, it’s clear that desert plants are champions of survival in a harsh ecosystem where water is so scarce.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Courtesy & Copyright Mark Larese-Casanova

US FWS images.fws.gov
Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.

Additional Reading:

Utah’s Desert Dwellers: Living in a Land of Climate Extremes. Wildlife Review. Utah Division of Wildlife Resources
wildlife.utah.gov/wr/0706desert/0706desert.pdf

Deserts. James MacMahon. The Audubon Society Nature guides. 1985. http://www.amazon.com/Deserts-National-Audubon-Society-Nature/dp/0394731395

Natural History of the Colorado Plateau and Great Basin, Harper, St. Clair, Thorne, and Hess (Eds.), 1994. http://www.amazon.com/Natural-History-Colorado-Plateau-Great/dp/0870815113

The Biology of Deserts, David Ward, Oxford University Press, 2009. http://www.amazon.com/Biology-Deserts-Habitats/dp/0199211477

 

Sagebrush

Sagebrush near Raft River, UT
Sagebrush near Raft River, UT – Photo Courtesy and Copyright 2007 Dr. Leila Shultz

Hi, I’m Holly Strand of Stokes Nature Center in beautiful Logan Canyon.

I was always prone to homesickness when I spent long periods in the Eastern US and abroad. Returning to Colorado for visits, I would break off a small branch of sagebrush to pack in my suitcase. That way I could always take some essence of home along with me. Now I don’t need to do that. The desert air and cold winters here in Utah make it a sagebrush heaven.

The scent that has become so dear to me comes from the volatile oils of the sagebrush plant. Ironically, the smell that appeals so much to me repels most animals. The aromatic properties of the sagebrush are a by-product of chemicals that evolved as a pest deterrent and as anti-freeze. Sagebrush oils have a very bitter taste. Browsers, such as deer and elk avoid the plants, nibbling on sagebrush only in winter months when the concentration of oils has decreased. And even then, only as a last resort. The pronghorn– a North American native that co-evolved with sagebrush–can tolerate it better than other herbivores.

Within the sunflower family, sagebrush belongs to the genus Artemisia – a group of wind-pollinated plants spread mostly across the northern hemisphere. The 400 or so species in this genus include a variety of sagebrushes, sageworts, and wormwoods.

The Atlas of Vascular Plants of Utah lists 19 different species in the Artemisia genus. Among the most common, you’ll find sand sagebrush in the dunes and deep sand regions in southern Utah. Black sagebrush is found on gentle, rocky slopes and windswept ridges in dry, shallow soils, in the foothills and desert mountain ranges. Bud sagebrush is common in salt-desert shrub communities from 4-6000 ft. Almost everywhere, however, big sagebrush dominates. It occurs in valleys, basins, and mountain slopes, at elevations between 2,500 and 10,000 feet. In Utah, you’ll also hear big sagebrush called Great Basin, Wyoming or mountain sagebrush.

Humans have put the unique qualities of sagebrush and its relatives to good use. The volatile oils are toxic to many intestinal parasites, therefore early Americans used it to rid themselves of worms. Oils have also been used to combat infections and to treat internal wounds. Eurasian wormwood–an introduced plant in Utah–is the defining ingredient, in the liquor absinthe, and is used for flavoring in other spirits and wines, including bitters and vermouth. The spice tarragon comes from dragonswort, an Artemisa species found in both Eurasia and N. America.

Ecologists used to think that the presence of sagebrush discourages or suppresses other forms of life. Certainly, sagebrush desert steppes are generally poor in species. The truth is that few species can tolerate the temperature extremes, soil conditions and lack of water the way that sagebrush can. So the next time you see some, pick a leaf, crush it, smell it, and admire this tough but well-adapted Utah native.

Dr. Leila Shultz, a Utah State University expert on sagebrush provided the science information for this piece.

Thanks to the Rocky Mountain Power Foundation for supporting research and development of Wild About Utah topics.
For Wild About Utah and Stokes Nature Center I’m Holly Strand.

 

Credits:

Photo Courtesy & Copyright 2007 Dr. Leila Shultz

Text: Stokes Nature Center: Holly Strand

Sources & Additional Reading:

Digital Atlas of the Vascular Plants of Utah, http://earth.gis.usu.edu/plants/index.html