Fabaceae: Peas and Beans: a Huge Family

And in many ways it may be the most easily recognized! While AsteraceaeClick to read the page
about the family... has the iconic sunflower, there are still many members of Asteraceae that are so unlike the iconic daisies that they can be overlooked as members of that family. Not so much with Fabaceae; that distinctive banner-wing-keel pattern is a consistent trade mark for the plants we see in El Dorado County, though there are some curious variations that appear in other regions that also will not be immediately recognized. Fabaceae, with more than 18,000 species, it is in third place for number of species worldwide (Asteraceae with 24,000, then—surprisingly!—Orchidaceae with 20,000, then Fabaceae.)

There are Three Subgroups of Fabaceae:

Caesalpinioideae: flowers slightly bilateral
Mimosoideae: flowers radial
Faboideae (previously Papilionoideae): flower clearly bilateral

While there are acacias (Mimosoideae, commonly called bottle-brush trees) 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...). Other than redbud, all of this county's native Fabaceae plants are members of Faboideae.

Caesalpinioideae: Only one member of this group is a California native:

“The latest classifications show that this subfamily is the most basal lineage among the legumes and the one from which the other two subfamilies evolved.” — Encyclopedia Britannica

Cercis (pronounced “sir-syss”; hear it on Answers.com) is unique for having the upper petals inside lateral petals (keel), and the leaves are not pinnately compound but are individual and more kidney-shaped.

Our notable native species is Redbud, Cercis occidentalis; it lines Hwy 50 through Cameron Park and can be found as high as Placerville. Other species of Cercis grow across the United States as natives. 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 actually buy one from a nursery as the seeds are difficult to germinate.

Mimosoideae:

The petals are very small; it’s the stamens that make the flower noticed. Good news! These are almost all tropical trees. There are only two families in this group that are native to California: Prosopis and Acacia, neither growing as natives in this county. Prosopis is called mesquite, with two native varieties in California; there is a single native acacia, A. greggii, (image shown) called "cat-claw" and it's a common southwest shrub.

Faboideae:

Common garden clover

One large petal (the banner) has a crease and stands up; two side petals (the wings) enclose two bottom petals (the keel) which are joined together. Distinctive and easy to recognize.

The example here is Astragalus coccinia, a particularly handsome plant that grows east of the Sierra in the desert areas. It can be found along the roads into Death Valley, for example, and is worth stopping to look at.

Examples from around your yard would include clovers and garden sweet peas. There are many species of clovers and they make a good starting point for looking at flowers with a magnifier. A 10x loupe will have you noticing construction details you likely have never noticed, and clovers offer surprises.

If your property includes Scotch broom you might consider removing it as it's an invasive plant.

Working to ID Plants in Faboideae...

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 simply separate a lupine from an astragalus. These plants are harder to identify mostly on finding how the parts are arranged inside the enclosing keel petals, and the hairs or lack of hairs on the keel itself. A microscope and some tweezers will let you investigate the stamens and answer questions about the upper edge of the keel.

Robinia, aka, Black Locust, (R. pseudoacacia), a tree that is listed as a "pest invasive", does grow in El Dorado County. There is large stand up Hwy 50 toward Camino, and there are trees growing along Green Valley Road near Rescue. 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.

Faboideae? 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 into two groups to include 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 "banner, wings, and keel": five sepals, five petals, ten stamens, and a pistil that develops a single row of seeds. This pod is called a legume.

pea pod A legume is a simple dry fruit that develops from a simple carpelA carpel is composed of an ovary, a style, and a stigma (see 10 Parts...) 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 peanutsDon't miss the interesting note below..., soybeans, lentils, and this surprise: jicama!

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

jicama 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 and 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.

Here's an interesting factoid about Peanuts:

Peanuts grow underground, right? And yet the peanut is not a root or corm or tuber. So what's up with that? If a seed (a peanut is a seed) grows from a pollinated flower, how does this one end up underground?

The peanut plant, Arachis hypogea, has the usual banner, wing, keel flower, but the flowers are always low on the plant. Once the flower is fertilized, the petals fall off and the pod starts to form, it points downward and actually pushes into the soil! It then orients itself horizontally and develops the seed pods that we know as 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. Click the picture for more info about peanuts, and notice the interesting leaf arrangement.

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