A plant that is adapted to living in dry conditions caused either by lack of soil water or by heat or wind bringing about excessive transpiration. Many xerophytes are found in deserts, on sand dunes, and on exposed moors and heaths. Some xerophytes, e.g. the * succulent desert cacti, store water in swollen stems and leaves. Many species reduce the rate of transpiration by having permanently rolled leaves, e.g. cross-leaved heath (Erica tetralix) or by having leaves that are rolled in dry weather, e.g. marram grass (Ammophila arenaria). Some have hairy leaves to trap moist air, e.g. great mullein (Verbascum thapsus) while others have stomata sunken into grooves producing pockets of moist air, e.g. Pinus. The leaves of many species are leathery with a thick cuticle and epidermis to reduce cuticular transpiration. Some species have stomata that close during the day and open at night (see crassulacean acid metabolism ). Compare hydrophyte , mesophyte. See also xerosere. |
