The Genus Baptisia in South Carolina

In my humble opinion, some of the most spectacular herbaceous perennials in our State are in the genus Baptisia. These beautiful native legumes share the generic common name of wild indigo, a name derived from their use as dyestuff plants by the Native Americans and early Europeans. In fact, Baptisia is from the Latin baptisis, or a dipping, relating to the dyeing procedure. The native American plant, Baptisia tinctoria, was cultivated in colonial times for a pale blue dye, but was a poor substitute for introduced Indigo (Indigofera tinctoria).

Baptisia species exhibit a peculiar trait of early canopy senescense. The canopy leaves and stems die and turn dark in late summer or early fall, considerably earlier than the first frost. The early change in color results from enzymatic reactions in the plant that create the blue pigment. This is most likely a day-length response. The senesced stems can break off at the soil level, thus creating a “tumbleweed”, which no doubt aids in dispersing seeds. A crown atop the sturdy taproot produces large sub-surface buds that give rise to next year’s plant canopy.

Members of the genus Baptisia are all nitrogen-fixing legumes, and as such, play an important role in providing fixed nitrogen for natural plant communities. They are all long-lived perennials with sturdy branched taproot systems. Baptisias are found on mesic to dry soil sites, and in open to partially forested sites where they get partial to full sun. Thus you can commonly spot Baptisias along road and utility rights-of-way, or in prairie-like, or glady sites.

Baptisia species are not seriously affected by pests. The most obvious insect activity on Baptisia comes from seed weevils. One such weevil is Apion rostrum, the adult of which lays her eggs in the young green pods, where the emerging larvae eat some of the forming seeds. Young adult weevils are commonly found when mature pods are opened to harvest the seeds. Scientists estimate that up to 25 percent of the seed production is lost to weevils. In addition, larvae of Wild Indigo Duskywing, Hoary Edge, Southern Dogface, and Orange Sulfur butterflies, and Black-Spotted Prominent moth can be found on Baptisia species, but larval herbivory never appears to be substantial, probably because Baptisias contain alkaloids called quinolizidines that are toxic to herbivores.

The Baptisias make wonderful contributions to our natural and planted landscapes. They produce copious flowers in a variety of colors. Plants can persist for many years in sunny to partially shaded sites. They have deep roots that allow them to survive droughty growing seasons, and can persist on poor acid soils, where they produce their own nitrogen fertilizer. Watch for them on you local naturalized roadsides next summer!

There are eight species of Baptisia found in South Carolina.

* Dr. Stringer is an Associate Professor Emeritus of Agronomy in the Department of Entomology, Soils and Plant Sciences, Clemson University, former State President and current Upstate Chapter President of the South Carolina Native Plant Society.