Alternate name: Horsefly-weed
Family: Fabaceae, Pea view all from this family
Description Smooth, bushy perennial with numerous few-flowered, elongated terminal clusters of yellow pea-like flowers.
Habit: native perennial herb; short, open, spreading habit; winter dormant.
Height: 1-3 ft (30-90 cm).
Leaf: alternate, pinnate, silver-green, clover-like; 3 small leaflets, 0.25 in (6 mm) long.
Flower: cream to clear yellow, sweet pea-like, 0.5 in (12 mm) long; in terminal spike to 3 in (75 mm) tall.
Fruit: round pod, green becoming black, beaked, 0.5 in (12 mm) long.
Warning This plant is poisonous if ingested, although no fatalities have been recorded. Sensitivity to a toxin varies with a personís age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plantís different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.
Flower May to September.
Habitat Open, dry, sandy sites: sandhills, pine flat woods, ridges, road banks, woodlands, fields, barrens, burnt fields; also cultivated as an ornamental and for medicinal use.
Range Across southeastern Canada; from New England south to Florida; west to Louisiana; north to Minnesota.
Discussion Also called horsefly weed, rattleweed, wild indigo. Threatened or endangered in Kentucky and Maine. In the autumn when fully mature, the plant turns silvery-grey and breaks off from the root system at ground level to form a tumbleweed. The pods stay with the plant for some time while the wind tumbles it around to new locations. Yellow wild indigo is the most widely distributed of the wild indigoes. It is the only known food of the larval stage of the wild indigo dusky winged butterfly (Erynnis baptisiae).
Some 15 other species are found in eastern North America, including numerous yellow species farther south and some white or creamy ones. Blue False Indigo (B.australis), which has upright racemes of blue flowers and sap that turns purple when exposed to air, has escaped from cultivation northward to New York and Vermont. The genus name, from the Greek baptizein (to dye), refers to the fact that some species are used as an inferior substitute for true indigo dye.