Plants adapted to living in dry environments such as succulents are termed "xerophytes". Nor are all succulents xerophytes, since plants like "Crassula helmsii" are both succulent and aquatic. Some xerophytes, such as cacti and other desert plants, have mucilage in their tissues. Popular examples of xerophytes are cacti, pineapple and some Gymnosperm plants. As compared to other plants, xerophytes have an inverted stomatal rhythm. Velloziaceae includes different xerophytes inhabiting open and dry habitats. Many succulent xerophytes employ the Crassulacean acid metabolism or better known as CAM photosynthesis. Many species grow in dry habitats (xerophytes) or tolerate salty soils (halophytes), some are ruderals. In xerophytes, parenchyma tissues store water. Most wild lettuces are xerophytes, adapted to dry habitat types. Ephemerals are the 'drought escaping' kind, and not true xerophytes. An evolutionary strategy employed by desert xerophytes is to reduce the rate of seed germination. Plants can be heliophytes, mesophytes, or xerophytes. Today the Garden is an outstanding landscape of xerophytes (dry-growing plants). Halophytes and xerophytes evolved to survive in such environments.