Plant of the Week
White Wild Indigo (Baptisia alba)
By Christopher David Benda
A fine plant is White Wild Indigo. In the Pea family (Fabaceae), this plant has an easily recognizable spike of white flowers. The name “Baptisia” means “to dye,” referring to some species with indigo flowers in this genus being used as a dye. The species name “alba” means “white,” obviously referring to the white flowers.
This is a large plant, herbaceous, but almost shrub-like with a tall inflorescence of many, white, pea-shaped flowers. Flowers are large, up to eighteen inches long, and occur at the top of the plant. Fruit is an oval pod with many seeds inside, and ripen from a green color to black.
The dried plants often act as tumbleweeds and roll along the land with the blowing wind, bringing along with them any remaining seeds still attached. Although it may take several years to reach maturity, white wild indigo grows quickly in the spring, its towering stature dominating over the other prairie plants. It is a long-lived plant and a legume, meaning it fixes nitrogen. Beneficial bacteria, called rhizobia, establish in the root nodules and put this limited nutrient in the soil for other plants to use. The rhizobia are in a symbiotic relationship with legumes; they both need each other to survive.
Despite a lack of floral scent, bumblebees love to visit the flowers, and fight their way inside the bulbous flower petals. It has alternate leaves, divided into three leaflets that are pointed at each end. Many species of caterpillars eat the leaves. Adult wild indigo weevils consume the plant and their young live in the seedpods and eat the seeds. It is extremely deep rooted and will persist in pastures and fields as it is poisonous and cattle tend to avoid it.
While this species is indicative of the tallgrass prairie, it will also occur in open woodlands and roadsides. Its range is centered in the Midwest, extends south to Texas and Florida.