xerophytes

Xerophytes are plants adapted to dry environments in which water is scarce or irregularly available. The term comes from Greek xeros, dry, and phyton, plant. Xerophytes are common in deserts, semi-arid regions, high-altitude plateaus, and coastal zones where evaporation exceeds rainfall, yet they persist through water-conserving strategies.

Adaptations fall into morphological, physiological, and biochemical categories. Morphologically, many xerophytes have small or lost leaves, thick or succulent tissues, a waxy cuticle, and protective features such as spines or dense surface hairs that reduce evaporation. Stomata are often sunken or protected in leaf pits, and the leaf surface may be coated with wax or hair to minimize water loss. Extensive root systems, either shallow and widespread or deep and penetrating, help exploit scarce moisture. Water storage tissues in stems or leaves and, in some species, the ability to rehydrate after drought aid survival.

Physiological strategies include Crassulacean acid metabolism (CAM) or, less commonly, C4 photosynthesis, which allow plants to fix carbon at night or under high daytime temperatures, reducing transpiration. Some xerophytes tolerate high soil salinity or have salt-excreting glands. Seasonal drought strategies vary from drought avoidance (rapid life cycles) to drought tolerance (long-lived, desiccation-tolerant tissue).

Well-known xerophytes include cacti and other succulents such as Agave and Aloe, as well as Euphorbia, Welwitschia, and many shrubs and grasses in arid regions. Xerophytes play a critical role in arid ecosystems, shaping microhabitats and contributing to soil stability and biodiversity. Their adaptations illustrate a range of plant responses to water scarcity.