Wild Indigo
Baptisia tinctoria
It derives its name from the bluish-black dye which can be extracted from the plant.
From Nearctica
Identification: Flowers yellow, pealike, arranged in irregular racemes. Stems and leaves may have a bluish bloom. Leaves with very short petioles or nearly sessile to the stem. Leaflets with blunt apices and widest near the apex. Leaf color gray-green, leaves turning black when dried. Plant 1 to 3 feet in height.
Distribution: Throughout most of eastern North America except in the south and west.
Habitat: Wild Indigo is a species of dry woods and woodland clearings.
Flowering period: May to September.
Similar Species: Wild Indigo could be confused with Birdfoot Trefoil. However the leaf of Birdfood Trefoil is divided into 5 leaflets, not 3. Blue False Indigo has blue or violet flowers.