Hosackia oblongifolia, synonym Lotus oblongifolius, is a species of legume native to western North America from Oregon to northern Mexico. It is known by the common name streambank bird's-foot trefoil or meadow lotus. It grows in moist to wet areas in several types of habitat. It is a spreading or upright perennial herb lined with leaves each made up of 3 elongated oval leaflets each up to 2.5 centimeters long. The inflorescence bears several yellow and white flowers between 1 and 2 centimeters long. The fruit is very elongated, reaching up to 5 centimeters in length but just a few millimeters in width.
Plants with copper colored flowers have been separated by some sources as var. cupreus, the copper-flowered bird's-foot trefoil. They are found in the Sierra Nevada slopes of Tulare County, California.[1]