Deserts are defined by dry conditions and extreme temperatures. They can be very hot during the day and cold at night. Some deserts even receive snowfall! Most deserts receive less than 25 inches of precipitation a year compared to approximately 50 inches of precipitation per year in Atlanta. Water is the predominant controlling factor for life in a desert and most plants and animals that live in a desert have special adaptations to the lack of water.
Desert plants are fascinating! They have wonderful names like Cow Tongue Prickly Pear, Hens and Chicks, Squid Agave and Pink Grizzly Bear Cactus. Those names reflect the interesting shapes, colors or spines that make desert plants awesome. Most of those characteristics help plants survive in harsh desert conditions by giving them the ability to collect and store water or reduce water loss.
Succulents are plants that store water in their stems, roots and/or leaves, which allow them to have some access to water during dry periods. Almost all cacti are succulents, but not all succulents are cacti. In the Atlanta Botanical Garden’s Desert House in the Fuqua Conservatory, there are no cacti! Cacti are primarily found in the Americas, and plants in the Desert House come from Africa and Madagascar. The plants in the Desert House and cacti evolved in dry climates and over time developed similar features like spines and fleshy stems. Genetically, however, cacti are very different from the plant families on display in the Desert House. If you would like to see a cactus, visit the Hardy Succulent Garden at the Atlanta Botanical Garden and look for plants labeled Cactaceae. To see what is inside a succulent, purchase an Aloe Vera leaf and cut it open. How does it feel, look and smell?
Desert plants have adaptations that prevent them from loosing water in bright, sunny and dry conditions. When walking through the Desert House at the Atlanta Botanical Garden you may notice that many of the leaves are small and some plants don’t even have leaves. This is to prevent water loss through transpiration. Desert leaves also tend to be lighter in color and can sometimes even look grey. Lighter colors reflect the sun better than darker colors (think about wearing white versus black on a hot, sunny day). There is plenty of sunlight in a desert, so most plants try to reflect sunlight to prevent water loss.
Discussion of desert plants is never complete without talking about their amazing defenses against hungry and thirsty animals. Some desert plants have deadly toxins in their sap, which makes them unappetizing or potential fatal to animals. Additionally, fuzzy hairs and sharp spines protect the plants from predators and can also provide important shade from the sun. Would you eat a plant with prickly spines and a poisonous center?
To see desert plants at the Atlanta Botanical Garden visit the Desert House in the Fuqua Conservatory and the Hardy Succulent Garden in the Outdoor Gardens. The Desert House features plants from South Africa and Madagascar and has some exciting plants such as desert orchids, medicinal rosy periwinkle, euphorbias and more. Outside in the Hardy Succulent Garden you can find plants from the Cactaceae family, some gorgeous agaves and get ideas about which desert plants can grow outside in the Atlanta area. Plus, you can see the Cow Tongue Prickly Pear. What do you think it looks like?