The plants that call the Sahara home are a vital resource for both the animals and the people that call the millions of square kilometers of the Sahara home, and over time they have adapted amazing resources that allow them to survive in an area where months can go by without so much as a rain cloud in sight.

Types of Plant Life Found in the Sahara

The Sahara desert is the world's largest hot desert, spreading across 8.6 million square kilometers of sand and oases in Northern Africa throughout the countries of Algeria, Chad, Egypt, Libya, Morocco, Mauritania, Mali, Niger, Sudan, Tunisia and Western Sahara. (Yes, there is such a thing as a cold desert-but that's a topic for another day.) Of those 8.6 million square kilometers, however, only 200,000 are fertile, fed by an intricate system of underground rivers, reservoirs and artisan wells.

The largest challenge that plant life faces in the Sahara is the lack of rain. Plants, like all living things, need moisture to survive. In an area where the average rainfall is four inches per year, approximately as much as many southern regions of the U.S. receive in a single thunderstorm, that's not an easy requirement. That isn't the only challenge these plants face, however.

The wide expanse of the Sahara means that it is home to one of the largest varieties of topical features on earth. The highest point of the desert is 11,204 feet above sea level at the top of Mount Koussi, an extinct volcano in northern Chad; the lowest is 436 feet below sea level in the Qattera depression in Egypt. There's nothing uniform about either the appearance or the form of the Sahara.

Areas of the Qattara depression and other areas in which the soil is rich in saline are home to a wide variety of halophytes, plants that thrive in salty habitats. Date palms are a common example. The highlands and more arid regions of the Sahara are home to Xerophytes, plants that have over time adapted to life in areas with very little precipitation and have learned to conserve and make the most of the moisture available to them.

There are several primary adaptations of Xerophytes that allow them to thrive in the dry regions of the Sahara:

1) Many plants have developed extensive root structures that allow them to reach up to 80 feet or more into the ground, connecting them to underground water sources that ensure they remain hydrated in between storms.

2) Succulents such as cacti and their African equivalent, the euphorbia (Euphorbia actinoclada is shown in the illustration to the right), have learned to conserve the moisture they receive each year, absorbing large amounts of water when it rains and storing it in their fleshy stems or leaves in preparation for drought. These plants have adapted even further by modifying their broad leaves into spines to prevent excessive loss of water as the result of evaporation and typically have a vast, shallow root system that rapidly absorbs as much water as possible when it reaches the ground.

3) Small, flowering plants known as ephemerals (annuals) have shallow roots that allow them to absorb maximum moisture from the occasional rainfall. These plants complete their growing cycle quickly, producing seeds that lie dormant until after the next rain. Their brightly colored flowers attract the insects that are vital to their rapid pollination.

4) Grasses develop an extensive root system that allows the roots to live deep in the soil even when the visible portion of the plant has died-or been scorched.

5) Geophytes spend the majority of their lives underground as bulbs, quickly producing flowers when the rains do come. Lilies and tulips are a common example of geophytes found in the United States, as shown in the excerpt below from "The Physiology of Flower Bulbs", published in 1993 in the Netherlands; geophytes in the Sahara and other regions of the Mediterranean are greatly herbaceous and tend to have a notoriously long juvenile period. They may live underground for years before flowering.

6) Shrubs and small trees in the Sahara are very similar to those found elsewhere in the world, with an extensive root system that penetrates deeply into the earth and leaves that are shed during the hottest part of the year.