Are all ‘beans’ related?
The word bean, is a term loosely used to describe to any legume whose seeds or pods are eaten. Legumes are classified under the family Leguminosae (Fabaceae).
The Common Bean (Phaseolus vulgaris L.)
Most beans were classified in the genus Phaseolus with the common bean, Phaseolus vulgaris. Common bean includes the following bean varieties: kidney bean, navy bean, Romano, Pinto bean, Pink bean, Flageolet, Cranberry bean and Black Turtle Bean. It also includes immature green beans, also known as, string beans or snap beans.
Other species in the genus Phaseolus include the following
Phaseolus lunatus (lima bean and butter bean): They are named after Lima, the capital of Peru, where they’ve been cultivated for since about 5,000 B.C. It’s the most common bean in the USA where it’s mostly sold frozen or canned.
Phaseolus acutifolius (tepary bean): Tepary bean is mainly grown in Mexico and Arizona (United States). It’s mostly grown for its mature dry seeds, which are eaten after boiling, steaming, frying or baking.
Phaseolus coccineus (runner bean):The beans are eaten fresh or dried. Immature pods are also edible. It’s grown for food and as an ornamental.
Vigna species: Green Gram, Black eyed pea and Adzuki bean
Many former members of the genus Phaseolus were moved to the genus Vigna and now species like Adzuki bean (Vigna angularis), Black gram (V. mungo), Cowpea or Black eyed pea (V. unguiculata) and Mung bean or Green gram (V. radiata) are members of the genus Vigna.
Confusing Common Names
Common names of beans are often confusing for example soya bean (Glycine max) belongs to the genus Glycine and not Phaseolus; Broad bean (Vicia faba) belongs to genus Vicia, Garbanzo beans (Cicer arietinum) belongs to the genus Cicer; Hyacinth bean (Lablab purpureus) belongs to the genus Lablab and jack bean (Canavalia ensiformis) belongs to the genus Canavalia, just to mention a few.
Totally Unrelated to Bean Family
The word bean is sometimes used to refer to the seeds or pods of plants that are not in the family leguminosae, but which bear a superficial resemblance to true beans, for example coffee beans (Coffea arabica, family Rubiaceae), castor beans (Ricinus communis, family Euphorbiaceae) and cocoa beans (Theobroma cacao, family Sterculiaceae), and vanilla beans (pods) (Vanilla planifolia, family Orchidaceae).