If you look at a flowering Wild Indigo (Baptisia bracteata ), you'll probably recognize the plant as a member of the legume family. The flowers certainly resemble those you'd see on pea plants. Each leaf is actually a cluster of 3 to 5 leaflets. They are considered palmate - the leaves radiate out from a point, much like as you look at your hand, your fingers radiate out from your palm.
The wild indigo has creamy yellow flowers, an odd contradiction to the name Indigo. Found in prairies or on rangeland, the flower stalks bend to the ground from the weight. The plains wild indigo blooms early in the season, so that insect pollinators are able to find the plants! Later in the summer, grasses would be tall enough to hide the flowers, making them more difficult for insects to find.
As the flowers mature, they develop into hard dark blue to black colored seed pods. If you look at a seed pod, more often than not it will be empty. Looking closely, you'll probably see a hole where an insect has emerged. According to the USDA,
"Parasitic weevils normally infest the seedpods in their native habitats. Generally, it takes a large number of seeds when they are harvested from a natural ecosystem to have any success at finding viable seeds."
When seeds do develop in the pods, they rattle when dry. The dry stems may break from the plant and be pushed across the open landscape, distributing seeds as they roll.
The plains wild indigo is about 1 to 2 feet tall. The plant does well in sunny, dry locations, but a seedling may take a few years to bloom.