Baptisia australis, commonly known as blue wild indigo or blue false indigo, is a flowering plant in the family Fabaceae (legumes). It is native to much of central and eastern North America and is particularly common in the Midwest, but it has also been introduced well beyond its natural range. Naturally it can be found growing wild at the borders of woods, along streams or in open meadows. It often has difficulty seeding itself in its native areas due to parasitic weevils that enter the seed pods, making the number of viable seeds very low.
B. australis is an herbaceous perennial that reproduces both sexually and asexually by means of its spreading rhizomes. The plant is erect and emerges from the rhizomatic network. The roots themselves are branched and deep, which helps the plant withstand periods of drought. When dug up they are woody and black in colour and show tubercles, wart-like projections found on the roots. The plant branches extensively about halfway up. The stems are stour and glabrous, or hairless. Broken stems secrete a sap that turns dark blue on contact with the air.