Fabaceae is the systematic name of the plant family that is commonly known as the Pea family. It consists of three subgroups: Caesalpinioideae, Mimosoideae and Papilionoideae (or better Faboideae). In modern systems like APG II this family Fabaceae is closely related to Quillajaceae, Polygalaceae or milkworts (including the families Diclidantheraceae, Moutabeaceae, and Xanthophyllaceae), and Surianaceae.
The leaves are usually alternate and compound, in the Mimosoideae and the Caesalpinioideae commonly bipinnate (e.g. Acacia, Mimosa). In many species the leaves have structures evolved to attract ants, that, being predatory, protect the plant from herbivore insects. Extrafloral nectaries -a gland secreting nectar -are common among the Mimosoideae and the Caesalpinioideae and are also found in some Faboideae (e.g. vetches Vicia sativa). Fabaceae are typically entomophilous plants (i.e. they are pollinated by insects) and the flower are usually showy to attract the pollinators.
Acacia dealbata "wattle"
diagram of the flower