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Pisum (garden pea; family Leguminosae, subfamily Papilionatae) A genus of annual herbs, many species of which climb by means of leaf tendrils. The leaves are compound, with paired oval leaflets. The flowers are zygomorphic with a distinctive petal arrangement: a large upright back petal and two smaller wing petals enclose a cup-like keel petal. The round seeds are borne in a long pod, and expelled explosively. P. sativum (garden pea) and other species are grown for their edible seeds and sometimes pods, used as a protein source for humans and livestock. They can be dried for storage. There are 5 species, occurring in the Mediterranean region and western Asia.