Like oxalis, black medic, with its three leaflets, is often confused with common clover. It is a dark-green annual with spreading prostrate, square stems which do not take root at the nodes. Leaflets are wedge-shaped with a small spur or tooth at the tip. The center leaflet is on a slightly protruding or extended stem. Bright yellow flowers are compressed into a small cluster. As each flower matures it forms a tightly coiled black seedpod containing a single amber-colored seed. Black medic, a member of the legume family, is fairly common all over the United States. A typical characteristic of this family is the tiny sacs, or nodules, of nitrogen that are attached to the roots.