Broadleaf stonecrop (Sedum spathulifolium, Crassulaceae) can often be found clinging to the rocky slopes of seaside cliffs and inland mountains from British Columbia through California. Although the clusters of small, bright yellow flowers get your attention, the leaves are perhaps more interesting:
This native perennial features unusual basal rosettes of succulent leaves that help it survive dry periods. These leaves are thickened and fleshy and can store water internally. They also have limited surface areas and waxy coats that inhibit water loss.
Stonecrops have also evolved to use crassulacean acid metabolism (CAM photosynthesis) to further conserve water. Most plants open their leaf pores (stomata) during the day, absorb carbon dioxide, and use it in conjunction with sunlight and water to generate sugar for energy. In arid conditions, however, this strategy results in a great deal of water loss through the pores.
CAM plants keep their pores closed during the day to conserve water. They open them at night when it’s cooler, store the captured carbon dioxide as malate, and then use it in photosynthesis on the following day. Although crassulacean acid metabolism was first observed in stonecrops and bears their Latin family name, it also occurs in thousands of other species, including cacti.