pea, hardy, annual, climbing leguminous plant ( Pisum sativum ) of the family Leguminosae (pulse family), grown for food by humans at least since the early Bronze Age; no longer known in the wild form. It is cultivated everywhere in home gardens and on a large scale commercially for freezing or canning. The round seed, borne in a pod, is a highly nutritious food, having a high protein and fiber content. The pod, too, of the varieties known as sugar peas, can be eaten, and the whole plant is grown for forage; the vines of garden varieties are also used for feeding stock. In New England many gardeners plant them on Apr. 19, the anniversary of the battle of Lexington—hoping to have their first peas by the Fourth of July, when according to traditional use they accompany salmon on the menu. Split peas are obtained from the field pea (var. arvense ), grown also for forage and as a green manure. About three quarters of the total world crop of the field pea variety is grown in China; much is used for stock feed. It is believed that peas were long grown only for use as pea meal, dried peas, or forage. Using peas as a green table vegetable began in the late Middle Ages, and the garden varieties were developed subsequently. The garden pea is renowned as the plant with which Gregor Mendel conducted the experiments that initiated the science of genetics. The chickpea and the sweet pea belong to different genera. Peas are classified in the division Magnoliophyta, class Magnoliopsida, order Rosales, family Leguminosae.