Deserts are delicate, if arid, ecosystems.
Deserts receive little rainfall during the majority of the year. Although most images of the desert include sand and saguaro, deserts occur at many elevations and even exist in cold climates. The lack of steady rainfall is the defining characteristic of the desert, yet resilient plants adapt to the harsh, arid conditions by utilizing various methods to conserve what little water they get from the environment. Does this Spark an idea?
Storage
Barrel cacti are uniquely adapted to harsh desert enviroments.
Many plants, like barrel cacti (Ferocactus sp.) and other succulents, store water in the plant's tissues. Deserts often receive heavy rains during seasonal wind shifts. Although much of the rainfall quickly dissipates, adapted plants quickly absorb the water for use in drier seasons. Plants may store water in thick leaves, within a central trunk, in underground, tuberous roots or use a combination of all three. The amount of water stored can be astounding; according to the Plant Sciences Center of Sierra Vista, one barrel cactus may store 24 pounds of water or more.
Transpiration
The narrow, waxy leaves of this yucca minimize water loss.
Desert-dwelling plant characteristics include waxy, coated surfaces and small, narrow or non-existent leaves. This prevents transpiration, the movement of moisture from inside the plant to outside. Waxy coatings seal the plant's surface, similar to plastic wrap over a bowl while the smaller surface area means there is less area for moisture to exit the plant.
Desert plants adapt at even the microscopic level. Stomates, or microscopic pores in the plant's surface, are open during the day and closed at night in the majority of plants. However, desert plants keep stomates open at night, when temperatures are cooler and water is less likely to exit the plant.
Growth Habits
Vertical growth reduces sun exposure.
Some desert plants grow leaves vertically rather than horizontally. This minimizes sun exposure, thereby reducing the surface temperature of the plant and keeping water from vaporizing. Alternatively, other plants produce a layer of small hairs, which break up the sunlight and reflect the heat. Desert plants also have extensive root systems to catch and store rainfall. The barrel cactus has a shallow root system that spreads over a wide area, while other plants have deep taproots that find groundwater.
Highly adapted plants may even reduce growth to the point of dormancy. Dormant plants use little to no water, returning to a growing state when conditions improve. The resurrection plant (Selaginella lepidophylla) is an example.
Tags: adapted plants, barrel cactus, exit plant, little water, other plants, plant surface, plants adapt