The authentic desert plants have had to adapt quite a lot in order to survive the scarcity of water.
One survival technique is to absorb all the water available and then store it in succulent tissue. Plants that store water like this are also called succulent, and the most well known of these belong to the cactus family, which includes more than 2,000 different species.
Cacti develop thorns in stead of leaves. These thorns are very useful: first, they are hard and very sharp, to dissuade animals that might try to devour a cactus; secondly, they provide shade for the stem and collect the dew; and third, the thorns traps trap a layer of air around the plant to reduce the amount of evaporated moisture, forming a barrier against the hot, dehydrating air.
Chlorophyll appears on the stems and on the exterior tissue of the plant,since there are no leaves. That way, photosynthesis can be carried out without wasting any water.
The Creosote bush is one of the most successful of all desert species because of its combination of many adaptations. Instead of thorns, it depends for protection on a smell and taste wildlife find unpleasant. It has tiny leaves which close their stomata during the day to avoid water loss and open them at night to absorb moisture. It has an extensive double root system to accumulate water from both surface and ground water.
Source: Llamas, Andreu, Plants of the Deserts, Chelsea House Publishers, New York, 1996.