Baptisia tinctoria
Researcher: Liz Drabik

Common Names:
horseflyweed (8)
rattle weed
yellow indigo
indigo weed (10)
American indigo
yellow broom
indigo broom
shoofly (18)
false indigo (19)

Genus: Baptisia , 22 species (8)

Family: Fabaceae (pea) (8)

Synonyms:
Baptisia gibbesii
Baptisia tinctoria var. crebra
Baptisia tinctoria var. projecta (8)
Sophora tinctoria (7)
Podalyria tinctoria

Relatives: Baptisia alba (white indigo);
Baptisia australis (blue false indigo);
Baptisia bracteata (yellow wild indigo)

Duration:Perennial

Habit: multi-branched, erect, bushy,
herbaceous

Height: Plants range from 2-4 feet in height.

Stems: The non-woody, glabrous stems (7)
are smooth, and colored yellow-green with
black dots (25).

Leaves: The smooth, clover-like,
bluish-green leaves are compound
alternate (19). Each is divided into three
½ inch leaflets on the stem (14).


©Thomas Schoepke - www.plant-pictures.com

Flowers: The hermaphroditic flowers are
bright yellow and irregularly shaped, each measuring about ½ inch long. They bloom at
the ends of
the stems in terminal racemes from early
summer until early fall, at which point they
mature into the seed-bearing pod.


Wild Indigo seed pod
Prairie Watch 2002

Fruit: The pods are dark brown, slightly puffy, and between 1-3 inches long. Each pod contains one oval, pea-sized, bluish-black seed. Seeds ripen throughout the fall.



Wild Indigo Root
University of North Carolina
Consortium on Natural Medicines

Roots: Baptisia tinctoria plants establish an extensive, although shallow, root system, with the round, fleshy root branching off into 2-foot-long rootlets. The compounds of medicinal interest are contained in the root, which has two layers. The thick, scaly, brownish-black bark protects the porous, off-white interior (25). It has no smell but is described as tasting acrid and bitter (25).

Pollination: insect

Habitat: Baptisia plants are often found in dry fields, clearings, and on the edges of woodlands. They thrive in well-drained, slightly acidic (pH 5.8-7) soils composed of sand or loam. Plants grow best in full sun but will tolerate partial shade.

Other Traits: Nitrogen-fixing Rhizobium bacteria live symbiotically on the root nodules of wild indigo, which lends plants the ability to fix atmospheric nitrogen. All parts of the plant blacken upon drying.

Associations:

Native Range: This United States native can be found from southern Canada down to Georgia , and as far west as Iowa and Minnesota .

Cultivation: rare

Pests/diseases: powdery mildew, stem diseases, and rust (19); exotic pests.

Other threats: Root rot and weeds pose a threat, especially during the first year; planting on well-drained raised beds and mulching are recommended prevention measures (15).

Conservation status: Baptisia tinctoria is endangered in Maine and Illinois (where it was thought to be extinct, but was rediscovered in 2004). It is considered at-risk in areas on the edges of the natural range, such as Iowa and Ontario , CA .  

History/culture: Native Americans used Baptisia tinctoria root to treat a wide range of maladies. Wild indigo preparations were applied externally to disinfect wounds and soothe inflammations, and ingested as a remedy for venereal disease, pain, and liver and kidney problems. Their use of wild indigo to create a weak blue dye inspired the nickname “false indigo”.

Wild indigo was also once known as “horsefly weed”, as farmers discovered that tying bunches of the plant to horses kept insects at bay. Doctors in the late 1800s-early 1900s recognized the potential of wild indigo to combat deadly illnesses, notably typhoid, smallpox, and scarlet fever (26). Botanical literature from this period documents Baptisia tinctoria as a treatment for ulcerations, gangrenous wounds, upper respiratory infections, and mouth sores, and states that it also fortifies red blood cells and promotes the flow of bile and digestive juices (25, 26).