Notes on the Fabaceae (Pea) Family

This page last modified on 21 March, 2006

Until a few years ago, this family of plants was known as Leguminoseae, which refers to the shared characteristic that the fruit of these plants is a Legume a.k.a. Bean a.k.a. pod of Peas. When the flowers are in bloom, one doesn't always have examples of the fruit available to see that they are like beans or pea pods.

This family is often broken into three subfamilies which have quite different flower characteristics, i.e.:

• Mimosoideae (Mimosa) - Characterised by dense clusters of long colorful stamens.
• Caesalpinioideae - Flowers with 5 petals that are slightly bilateral, but at a quick glance often look radial.
• Papilionoideae - Bilateral flowers, with the characteristic large banner petal, two smaller wing petals on either side, and two partially fused keel petals which usually are nestled between the wing petals.

Some botanists consider these to be separate families, rather than subfamilies, and the identifications are likely to change over time as the relationships become better understood.  Of the subfamilies, the Papilionoideae are most numerous and diverse.  In fact several genera within the Fabaceae have so many recognized species in California that I have chosen to separate the family into 6 "subfamilies" for visual identification purposes in this key.  5 of the 6 refer to subgroups within the Papilionoideae.  The "subfamily" FabaceaeRadial refers to both the Mimosoideae and the Caesalpinioideae, because the flowers of the latter are almost radial. (When time permits, I will add duplicated examples of these to two or three other top level branches of this visual key.)

A more detailed and helpful description of the Fabaceae characteristics may be found in California Desert Wildflowers, by Sia and Emil Morhardt, University of California Press, 2004.