Perennial desert plants have evolved three major ways to deal with the harsh desert environment.
The plants take up rainwater rapidly through a mass of tiny roots. They can survive a prolonged dry season by storing a lot of water in their tissues. They conserve water by having a slow rate of transpiration, thus reducing water loss through their stomata or pores.
The acacia plant, for example, has an extensive network of fine roots deep in the soil to capture moisture all year round. Long roots enable plants to tap water deep underground even during the driest times. Other species such as the cereus have bulbous roots to store water.
Some succulents and cacti absorb water during the wet season and store it in their tissues. Cells in the leaves and stalks swell up to help support the plant.
Some plants develop small spiky leaves and a waxy coating to minimise evaporation rates. The cacti minimise their transpiration rates by closing their stomata during the day.