Leaves, organs that grow from the stems of the higher plants. Leaves range in length from less than one inch (a few millimeters) in duckweeds to more than 50 feet (15 m) in some plants. The chief functions of leaves are to make food for plants and to free them of excess moisture. In some plants leaves also trap insects, which are used as food. Some plants reproduce themselves by means of leaves.
The leaves of many plants are important foods. Cabbage and lettuce, for example, are eaten by humans, and the leaves of grasses and other plants nourish cattle, sheep, and horses. The leafstalks of some plants, such as rhubarb, celery, and celtuce, also are foods. Bay leaves and the leaves of parsley, sage, marjoram, and many other plants are herbs used to flavor foods.
Tea leaves and tobacco leaves are the bases of great industries. Flavorings and perfumes are obtained from the leaves of peppermint, spearmint, wintergreen, and many other plants. The leaves of many plants, including belladonna, coca, and digitalis, yield useful drugs. Dyes are obtained from the leaves of henna and indigo plants. Leaves also provide material for clothing, basketry, and roofing.