Phaseolus vulgaris, the common bean (also known as the string bean, field bean, flageolet bean, French bean, garden bean, green bean, haricot bean, pop bean, or snap bean), is a herbaceous annual plant grown worldwide for its edible dry seed (known as just "beans") or unripe fruit (green beans). Raw or undercooked beans contain the toxin phytohaemagglutinin. Its leaf is also occasionally used as a vegetable and the straw as fodder. Its botanical classification, along with other Phaseolus species, is as a member of the legume family Fabaceae, most of whose members acquire the nitrogen they require through an association with rhizobia, a species of nitrogen-fixing bacteria.