Author: Simone Maimon
Editors: Misha Wichita, Viola Chen
Artists: Kevin Lin
When one imagines a desert, a scalding, sandy, barren landscape lacking life across vast stretches of land comes to mind. But the Arctic and Antarctic contain deserts, with frost and frigidity replacing the commonly-known sand and sultry. Furthermore, there are deserts, such as the Chihuahuan Desert, that fluctuate between extremely hot and cold temperatures over one day. Over 20% of Earth’s landmass is desert—and not all of it is lifeless—so how exactly do plants survive in these harsh conditions?
Although it seems like the only thing they share is their intimidating polarity, deserts are defined as areas that receive less than ten centimeters of rain a year. For reference, the United States, which contains four major deserts, experienced seventy-five centimeters of rainfall in 2023. Therefore, desert plants have evolved adaptations that allow them to adjust to an environment that lacks this essential resource. Nature’s hostility has created some of the most distinct species and desert plants are no exception. Most plants can only live for two weeks without water, but some desert plants can live for years without it. There are three main types of desert plants: succulents, drought-tolerant plants, and drought-avoidant plants.
A cactus, the most stereotypical desert plant, is categorized as a succulent. Succulents are one of the most commonly gardened plants because of their beautiful colors and are generally easier to take care of than other plants because they don’t need to be watered as often. These plants can absorb and store large amounts of water, to ensure their survival until the next rainfall. Succulents also have a few adaptations which allow them to keep water. Structurally, these plants minimize their surface area and create a waxy outer layer to prevent water evaporation. Succulents tend to stretch their roots horizontally rather than vertically because this allows them to absorb more water in a faster manner. Most interestingly, many succulents undergo a unique version of photosynthesis: Crassulacean Acid Metabolism (CAM) photosynthesis. CAM plants store their carbon dioxide at night as a substance called malate, which is used throughout the day to undergo photosynthesis. Because plants no longer have to open their pores when the sun is setting to take in gas, this adaptation decreases the amount of evaporation. In especially long droughts, CAM plants start to slow their internal processes—decreasing the amount of resources they consume to conserve themselves. Once it rains again, succulents can go back to functioning normally in just a few hours; other desert plants that can also slow their internal processes cannot restart them as quickly as succulents can.
A second type of desert plant is drought-tolerant plants. During dry seasons, these plants usually shed their leaves and stop photosynthesis entirely to conserve nutrients for long periods. These plants have longer alternation cycles between slow and fast metabolic states; it can take them up to two weeks to restart their metabolism once slowed. This is because drought-tolerant plants extend their roots deeper—the deepest roots cannot absorb rainwater until after it has seeped into the earth. But deeper roots allow a plant to draw more moisture from the soil and so these plants remain dormant for a longer time. Although these plants have more downtime when switching between conservation and growth stages than succulents, they thrive in their metabolically active stage, which can last for several weeks because they can draw out more water. The plant stops growing and starts conserving once it completely dries out the soil.
The last type of desert plants, ones that have adapted to be drought-avoidant, are named annual plants, or annuals. As the name implies, an annual sprouts, and dies, within one year. In the fall, these plants start their lives, sprouting many leaves from a single seed embedded in the soil. During this season, seeds can successfully grow with next to nothing—one inch of rainfall is sufficient to germinate. In the winter, these plants are similar to drought-tolerant plants, and slow their metabolism for the whole season. When the milder spring conditions arrive, these plants bloom their flowers and use all their energy to spread their seeds. These seeds germinate again once the right conditions are achieved, which is typically in the fall. Due to their parent’s sacrifice, these seeds are resilient; even after ten years in a hostile environment, some can still germinate into robust plants that will survive to produce the next generation of seeds. What sets these plants apart is that they use nearly all their resources to maximize the chance of their offspring’s survival, completely dying when the harsh summer comes. But this is how the species can avoid the drought. Even if every individual plant lives for less than a year, they continue to thrive as a species.
All in all, Arctic desert adversity has produced some of the most fascinating plant species that can fight off the polar conditions to survive. Nothing new is created without challenges, and these plants are a great example of nature’s resilience.
Citations:
“Desert.” Education, education.nationalgeographic.org/resource/desert/. Accessed 24 Apr.
2024.
“IBISWorld - Industry Market Research, Reports, and Statistics.” IBISWorld Industry Reports, www.ibisworld.com/us/bed/average-annual-precipitation/489/. Accessed 24 Apr. 2024.
Nunez, Christina. “Desert Information and Facts.” Environment,
www.nationalgeographic.com/environment/article/deserts. Accessed 24 Apr. 2024.
“Yecora Region.” Arizona-Sonora Desert Museum,
www.desertmuseum.org/programs/succulents_adaptation.php. Accessed 24 Apr. 2024.
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