We all have a basic concept that plants require water and/or soil moisture for everything, right from germination to growth and development. Thus, when we think of dry desert and plants, they sound unrelated to each other. Considering the high temperature and prolonged dry spells prevalent in desert regions, there is no such solid aspect that supports desert vegetation. So, what is so special about desert plants that enable them to thrive in extreme conditions? In this article, we will try to learn about desert plant life and the characteristic features of desert plants.
Desert Biome: Plant Life
The ultimate example of desert plant is cactus. We often visualize several thorny cactus at the mere mention of a desert biome. It is true that several cactus species make up the predominant plant variety in desert areas, but there are more in the desert flora list. Some signature plants include brittle bush, jumping cholla, joshua tree, yucca, desert ironwood, and creosote bush. These desert plants (collectively known as xerophytes) have adaptive features that are responsible for their survival in the harsh environmental conditions, which other regular plants fail to thrive. Here, I am presenting some of the points that encourage plant life in the desert and the basics of desert plant survival.
Desert Plant Adaptations
There is no clear evidence about the evolution of desert plants, specially their features. In fact, there are no fossil records of cactus, despite their distribution over a large area. Hence, it is still doubtful as to when desert plant adaptations are developed. Scientists are of the opinion that they acquired specific attributes millions of years ago, as a response to the changing surrounding conditions. In other words, they are forced to develop adaptations for coping up the least hospitable conditions. As soon as raining starts, the plants sprout, grow, flower, and bear fruits (if applicable), thus completing the life cycle within a short time.
Desert Plant Root System
A typical desert plant has a deep root system, which is a specific physical mechanism. As the roots grow deep down the soil, they absorb soil water, which is then transported to the upper portions of the plant. Plant varieties that have adapted by developing very long roots are collectively known as phreatophytes (e.g mesquite tree with roots more than 50 feet long). Contrary to this, certain plants including cactus have shallow roots that extend in a radial manner to absorb as much moisture as possible during seasonal rains. Some xerophytes do have both radial and long root systems to absorb moisture.
Desert Plant Stem
One of the most profound characteristics of these plants is their ability to store water in any of the parts - roots, stem, and leaves. Take the example of cactus; they store water in the green, flattened, succulent stem called phylloclade. These leaf like structures perform photosynthesis to manufacture food and function in the same way as a typical leaf of regular plants. They also have a thick waxy coating that helps in retaining water as far as possible and protecting the plant from scorching heat. As per plant evolution studies, cactus are believed to be the xerophytic version of the rose family.
Desert Plant Leaves
Desert plants bear small foliage with waxy surface to minimize transpiration (loss of water through stomatal pores), which in turn, helps to conserve water. The foliage of succulents serves another function of storing water. Also, the stomatal opening of some xerophytes remains close during daytime and open at night, thus lowering the rate of transpiration. Coming to cactus, there are no true leaves. Rather they are modified into prickly spines for reducing water loss and protecting themselves from animals. Likewise, many other plants adapt to the area by developing thorns.
Even though plants require optimal growth conditions in average ranges, they develop certain adaptive traits to survive in the existing environment. Perennial desert plants remain inactive during hot dry spells and become active with the arrival of rainy season. Whereas, annual desert plants absorb water from rain and complete their life cycle quickly. This is how we get to enjoy the scenic beauty of desert wildflower blooms and cactus flowers with shrubs and trees in the background. The main worrying issue that disturbs the current desert vegetation is loss of nitrogen from soil due to increase aridity.