Fabaceae is commonly called the pea / bean family. It is the third biggest plant family after Orchidaceae (orchids) and Asteraceae (daisies) with approximately 700 genera and 18,000 species. There are three sub families within Fabaceae, Papilionaceae, Casalpinaceae (the cassias) and Alimosaceae (the acacias). The flowers of the species are constructed the same, although in differing proportions. There is one large upper petal (banner) behind two smaller petals (wings) and the lower petal (keel) are fused together.
The fruit is also the same across the genera, a narrow pod, opening at the sides, with the seeds in a row inside. Another characteristic that Fabaceae share is their nitrogen fixing properties. They have a fibrous tap root with nodules in which nitrogen fixing bacteria (Rhizobia) live.
An interesting fact about this family is that they are all edible or barely edible. All contain levels of a poisonous alkaloid that inhibits an enzyme necessary for mammals' metabolism. This poison is in the whole plant but especially in the seed coat. Excessive consumption of the seemingly harmless garden pea for example could cause depression and nervous disorders.