Allelopathy: when an organism produces chemicals that change the growth or survival of another organism.
Perennial: living or being present for many years.
Tap root: a long and mostly straight root, like a carrot.
Toxin: a poisonous substance made by plants or animals. Snake and spider venom are a type of toxin... more
Transpiration: the release of water from tiny openings in the leaves of plants (stomata). This process causes movement of water throughout the plant from the roots to the leaves.
Xerophyte: a plant that is able to survive in areas with very little water.
The desert is a difficult place to be a plant because of the dry, hot air. To move nutrients up their roots, plants evaporate water from their leaves in a process called transpiration. But in the desert, where water is hard to come by, many plants have adaptations to help save water. The plants can save water a few different ways: they can control the amount of water lost by transpiration, the amount they can get, or the amount they can store. If a plant has adaptations to help them deal with desert weather, we call them xerophytes, a word that means dry plants.
Cactus and other plants that store lots of water to help them through the dry seasons are called succulents. During even light rains, these plants soak up as much water as they can hold, storing the water in large storage areas in roots, leaves, or plant stems.
Some plants only live and grow during the wet season, producing seeds that can tolerate the dry season. These plants are called annuals, because they reappear every year. Thus the adult plant, which loses more water than the seed, avoids the hot and dry conditions of the dry seasons.
Other plants called perennials live for several years, but may go dormant or inactive during the dry season.
A lot of desert plants don’t store a bunch of water or die or become inactive during the dry season. Instead, these plants are able to tolerate or withstand the hottest and driest parts of the year.
A few different tricks help these plants handle the desert conditions. The sharp spines that you see on cactus and some other plants help shade the plant from the sun, keeping it cool. Certain plants like mesquite trees grow very long tap roots, reaching down over 100 feet to reach the groundwater, water stored deep underground.
For some plants, one way to make sure to get enough water is to get rid of the competition—that is, nearby plants. A plant called creosote makes special chemicals, or toxins, that they release into nearby soil. These toxins make it difficult for other plants to grow in that soil. This trick is called allelopathy, and it keeps away plants that would use up the creosote’s water supply.
Images via Wikimedia commons. Additional image by Duff Axsom.
Karla Moeller. (2013, July 24). Plants of the Desert. ASU - Ask A Biologist. Retrieved October 24, 2020 from https://askabiologist.asu.edu/fr/plants-desert
Karla Moeller. "Plants of the Desert". ASU - Ask A Biologist. 24 July, 2013. https://askabiologist.asu.edu/fr/plants-desert
Karla Moeller. "Plants of the Desert". ASU - Ask A Biologist. 24 Jul 2013. ASU - Ask A Biologist, Web. 24 Oct 2020. https://askabiologist.asu.edu/fr/plants-desert
Desert plants come in all types, shapes, and sizes, like this succulent that is called the spiral aloe plant.