However, some weeds and ground cover are especially problematic to find in your yard. One such plant is the birdsfoot trefoil (Lotus corniculatus). The plant is a perennial ground cover that may reach up 2 feet in height. Birdsfoot trefoil is native to parts of Asia and Europe, but was introduced into the U.S. to help manage erosion and to fix nitrogen as other peas and legumes do. Unfortunately, the plant grew out of control.