Some plants have leaves that perform functions other than photosynthesis. While the tendrils of some plants are modifications to the stems and provide support for the plant, in other species, such as pea plants (Pisum sativum), the tendrils are modified leaves. In carnivorous plants, such as the Venus flytrap (Dionaea muscipula) and the pitcher plant (Sarracenia purpurea), the leaves attract, capture, and digest the insects with enzymes. Other examples of modified leaves include certain desert plants: Many grow mainly underground, with only a small transparent “window” tip protruding above the soil surface—allowing light to penetrate and reach the site of photosynthesis. The soil covering the leaf protects it from dehydration by the harsh desert winds.