Fabaceae is a Huge Family

And in many ways it may be the most easily recognized! While Asteraceae has the iconic sunflower, there are still many members of Asteraceae that are so not like daisies that they can be overlooked. Not so with Fabaceae because that distinctive banner-wing-keel pattern is a consistent trade mark. With more than 17,000 species, it is in third place for number of species worldwide. There are three subgroups:

While there must be acacias (Mimosoideae)planted ornamentally in lower elevation yards in El Dorado County, our main concern will be with the bilateral flower groups; there is but one species from Caesalpinioideae and that one is the attractive redbud (see note below) which is the attention-getter as people travel through the chaparral belt up to about 2000' elevation. Other than redbud, all of our native Fabaceae plants are members of Faboideae

Mimosoideae: Good news! These are almost all tropical trees. We have only two families in this group that are native to California: Prosopis and Acacia. Prosopis is called mesquite, with two native varieties in California; there is a single native acacia, A. greggii, called "cat-claw" and a common southwest shrub.
El Dorado County has no native species from this group, but Robinia, aka, Black Locust, (R. pseudoacacia), a tree that is listed as a "pest invasive", does indeed grow in El Dorado County. In fact I'm pretty sure that the large stand of "mystery trees" I have looked at for a few years as I drive up Hwy 50 toward Camino must be Robinia? The trees are tall and have white flowers. I have camped under Robinia in places along Hwy 395 (eastern Sierra) and must admit they have a sweet fragrance that I enjoyed.
Caesalpinioideae: Only one member of this group is a California native: Redbud. Cercis occidentalis; other forms of Cercis (pronounced "ser-syss") grow across the United States as natives. Cercis leaves are not pinnately compound but individual and more kidney-shaped. Redbud is one plant that can be positively identified from a car at 40 mph because of its mass of pink flowers in Spring, or its distinctive wine-colored foliage in Autumn. The shrub is a fine addition to a native garden, but you may want to acually bu one from a nursery as the seeds are difficult to germinate.
Faboideae: So now comes the heavy lifting; plants in this subfamily are hard to identify to species, but not too hard to get to know if you're satisfied to know a lupine from an astragalus. These plants are harder to identify because of the many ways the parts are arranged inside the enclosing keel petals. A microscope and some tweezers will let you investigate the stamens and answer questions about the upper edge of the keel.

Faboidiae? What about Legumes?

Indeed. In fact the whole family was once called Leguminoseae (legumen being Latin for bean), Continuing research resulted in splitting and refining the groups. Fabaceae (fava being another Latin word for bean). If you know the common sweet pea flower, you can recognize the flowers in this group: lupines, clovers, vetches, etc., all share the basic "flag, banner, keel": five sepals, five petals, ten stamens, and a pistil that develops a single row of seeds. This pod is called a legume.

A legume is a simple dry fruit that develops from a simple carpel and usually dehisces (opens along a seam) on two sides. A common name for this type of fruit is a "pod", although pod is also applied to a few other fruit types. Well-known plants that bear legume fruits include alfalfa, clover, pea, bean, and peanuts. A peanut is not a nut in the botanical sense; a peanut is an indehiscent legume, that is, one that does not spontaneously split open along a seam.

Wait a minute! Faba from fava?

"The Latin alphabet was created from the early Greek alphabet by taking over letters representing sounds common in the two languages, and adapting the others for Latin sounds that did not occur in Greek. The letter B represented the voiced labiodental sound in Greek (English v), but Latin used it for the voiced labial sound (English b). This B-V uncertainty was a feature of later Latin, as it yet is in modern Spanish, where vino is pronounced bino. The Latin alphabet was established before the Greek alphabet was regularized in Athens. All this is only so that you recognize the close relation of the two alphabets, and some of the reasons for the differences."—University of Denver site

Faboidiae plants are still commonly called legumes and they are some of our the valuable food crops grown: beans, peas, peanuts, soybeans, lentils, and a surprise: jicama!*. Other members of the family are grown for animal feed or green manure, such as clover, alfalfa, cassia, and soybean. Jicama (Pachyrhizus erosus) is the root of a bean plant! It is tasty vegetable that is simply peeled, sliced, and eaten raw. It has a crispy texture, a slightly sweet flavor something like an apple. It contains a high amount of vitamin C, is low in sodium, and has no fat. One serving of jicama (about one cup) has only 45 calories.