Many members of Caryophyllales are adapted structurally or physiologically to extreme environments such as deserts, high-alkaline soils, high-saline substrates, and nutrient-poor soils. They have conquered these habitats through a variety of adaptations such as unusual photosynthetic pathways (crassulacean acid metabolism, CAM, and C₄ as opposed to C₃ photosynthesis), unusual morphologies (e.g., succulence), secretion of excessive salt by special glands, and unusual methods of nutrient uptake (e.g., carnivory). Given the distributions of these adaptations across Caryophyllales, it appears that most of these adaptations have arisen many times.