Creeping indigo is an invasive weed that can cause life-threatening liver disease and neurologic signs in horses that eat it. | Photo: Wikimedia Commons/Denis Barthel

—Debra Harris Taylor, via Facebook

A: There are two species of creeping indigo (also known as lawn indigo or trailing indigo)—Indigofera spicata and Indigofera hendecaphylla—that are very similar in appearance, and their identities are often confused. Both species are prostrate (grow flat across the ground), spreading perennial herbs that grow to 18 inches in height and 3 feet in diameter, with a strong, woody taproot (the central downward-growing root). Flowers can be pink, red, or white. Seed pods are typically leguminous (pealike). I. spicata has a short, 3-inch-long inflorescence (cluster of flowers on the branch), while I. hendecaphylla has a 4- to 5-inch inflorescence. The latter also has longer seed pods with distinctive beaks.

Both species are native to Africa’s higher rainfall areas and have since been introduced to many tropical areas of the world. In North America, I. spicata grows predominantly in Florida, where it has established itself as an invasive pasture and lawn weed. It spreads readily by seed