Tricks of the Trade....How Desert Plants Survive
How do desert plants save water?
How do plants get water?
One way desert plants, trees, and shrubs suck up as much water as possible is by growing very deep taproots. Sometimes these roots can get to be more than 100 feet long. The above ground plant parts may remain small for years simply because the plant puts most of its energy into developing its taproot system. Desert plants may have a huge, tangled network of shallow roots that spread out from the plant in all directions. The roots can be as long as the plant is tall, and can quickly absorb water from the slightest rainfall.
Why do plants shrink and swell?
Desert plants can soak up water, store it, and prepare to use it during drought. For example, cacti and many other desert plants store water in their fleshy leaves and stems. Desert plants may also have other adaptations for water storage, such as pleats or folds that will allow the plant to swell with added water when it can. The pleats or folds can almost disappear if the plant soaks up a lot of water; then the plant can shrink, and its pleats or folds can become visible again as drought sets in and the plant makes use of water it has stored. Though many desert plants die to the ground during the hottest part of each year, the water they have stored in underground roots, tubers and bulbs will sustain them until the next moist period.
Why do plants grow hairs and spines? The hairs and spines that grow on desert plants help reduce moisture loss by breaking the effects of the wind. They also help to cast minute shadows on desert plants, which can protect them from the sun. The hairs and spines can even serve to reflect the sun's rays away from plants because of their shininess. Lastly, hairs and spines can help protect plants from hungry animal predators.
Why do plants produce special chemicals?
Scientists believe that desert plants may produce and give off chemicals from their leaves or roots that keep other plants from growing nearby. It is thought that plants do this to reduce competition, especially when water is scarce.
Why do seeds of plants sleep?
Some desert plants cope with the desert's dryness by not coping at all. As a result, during drought they are present only as seeds in the soil. For months, years, or even decades these seeds "sleep" to wait out the dry spell in a dormant state. When the right amount of rain falls and soaks into the soil, they sprout and bloom. When this happens the desert's dry brown landscape can quickly change into colorful fields of wildflowers, herbs, and grasses. Most of these fast-growing desert plants do not last very long. So aside from having seeds that are adapted to drought, they have few or no special adaptations to desert conditions. This is why desert plants of this kind sprout, flower, and leave behind a generation of seeds as quickly as possible. Short-lived desert plants like this are called ephemerals. With little water available to help them grow, dormant ephemerals are covered and protected by natural chemicals called inhibitors. The primary function of inhibitors is to keep seeds from germinating until enough moisture and specific temperatures are present. One the inhibitor has been washed off, the seeds can sprout.