The Legumes (Family Fabaceae)

The legumes are exceptionally important plants of the grassland woodland ecosystem because they are a very important food source for animals. They produce nectar from the flowers and protein from the seeds (the peas and beans). The legume seeds (the beans and peas) tend to hold their protein content longer than the grasses and other forbs in late winter. In addition, they enrich the soil by their symbiosis with nitrogen fixing bacteria (rhizobia and other bacteria) within the root nodules of the plant. The rhizobia take nitrogen from the air and convert it to nitrogenous compounds, such as ammonia, nitrate and nitrogen dioxide usable by plants, including the host legume, and other organisms.

Legumes represent the third largest terrestrial plant family on Earth, following the orchid and sunflower families.

Coral Bean Erythrina herbacea

Coral Bean, Erythrina herbcea, is one of the showiest bloomers on Wafer Creek Ranch. Known as Mamou in south Louisiana, other common names include coral bean and Cherokee bean. Its range is rather restricted to eastern Mexico, coastal Texas, Louisiana, and for the most part hugging the coast eastward on to Florida and South Carolina. Coral bean blossoms are excellent nectar providers to hummingbirds and some insects, but the shiny bright-red beans are highly toxic to humans. In north Louisiana coral bean grows like a perennial forb due to its sensitivity to freezing but farther south it will exist through the winter as a shrub or small tree. 

Desmodium sp.

Desmodium is the genus for a number of species which, unfortunately, I cannot sort out. But then, neither can many botanists. The multiple species on Wafer Creek Ranch are robust plants that are excellent providers of wildlife food from the bean pods (loments). Also, Desmodium is a host plant for certain butterfly species. I think we are all familiar with Desmodium if only because they are the culprits from which we collect the beggar lice (sticktights) on our clothes when we enter a weedy area in fall. Perhaps we shouldn’t be surprised as the plant has little pink flowers that stick their tongues out at us.

Desmodium bean pods (loments) on a very large Desmodium leaf.

Hairy (Bush) Lespedeza Lespedeza hirta

Hairy Lespedeza, Lespedeza hirta, will serve here as the lespedeza prototype for our brief legume tour, mainly because it is a large (up to four feet tall) and showy plant. The lespedezas are generally upright, largely unbranching, vertical growing legumes with a narrow conformation. As with many, but not all, legumes, their leaflets grow in threes (trifoliate). Hairy lespedeza has a large range extending from Canada south through the southeastern U.S. and Midwest. The plant is quite special in that it serves as larval host plant to many moth and butterfly species. Plus, it’s a good nectar provider for insects. 

Pink Fuzzybean Strophostyles umbellata

Hardly a presentation of the tallgrass prairie plant community would exclude the little Pink Fuzzybean, Strophostyles umbellata. The plant’s flower is distinctive having a somewhat umbrella shape and a twisted keel, the central-bottom part of the blossom. Common in the southeast and southern Midwest, the flowers are nectar providers for insects and the beans are food for wildlife. Pink Fuzzybean is a good example of a perennial legume forb that grows as a vine.

Partridge Pea Chamaecrista fasciculata

Partridge Pea, Chamaecrista fasciculata is a common native annual legume throughout most of the Midwest and eastern North America. The flower is pollinated only by long-tongued bees such as bumble bees, honey bees and others. Though the flowers produce pollen, they do not produce nectar. The leaf stems serve as extrafloral nectaries where insects can gather the nectar. Though partridge pea is a low C-value forb, it is very important in the ecosystem as it produces nectar for insects and the pea pods are an excellent winter food source for birds and mammals. Partridge pea stands two to three feet tall and each plant produces a large number of pea pods.   

Partridge Pea with its numerous pea pods

Climbing Butterflypea Centrosema virginianum

Climbing (or Spurred) Butterflypea, Centrosema virginianum is a common native perineal forb of open sunny areas with a range including the southeastern U.S., southern Midwest and extending far to the south including South America to Argentina. It is a vine legume and excellent for wildlife because of its nectar consumed by bees and its elongate seedpods eaten by birds and mammals.

Sensitive Briar, Mimosa nuttallii
w/pink pompom flowers

Sensitive Briar and its “starfish” seedpods

Sensitive Briar (Catclaw Briar), Mimosa nuttallii, is a creeping, thorny vine legume of the Midwest. It is a perennial and an important nectar provider for insects and the leaves and seeds are eaten by mammals and birds. The plants exhibit seismonasty, meaning the leaves are sensitive to touch, wind and darkness that causes the leaflets to fold. The flowers are interesting pink pompoms and the seedpods are unique, forming prickly “starfish” arrangements.

Goat’s Rue, Tephrosia virginiana. Opal in background.

Tephrosia virginiana, Goat’s Rue, is a high-C value perennial legume forb of the Midwest and eastern North America, and provides a food source for birds and mammals. Insects gather the nectar and several species of insect use it as a larval host plant. Unfortunately, goat’s rue is distinctly rare on Wafer Creek Ranch, but it would have been common in the historic grassland ecosystem of the shortleaf pine-oak-hickory woodland.

---

Conservationist and retired medical doctor (pathology), Johnny Armstrong and his wife Karen and Opal (k-nine) live within a Nature Conservancy protected old-growth forest and woodland near Ruston, Louisiana. Shadowshine is his first novel..