Peirson's Milkvetch (Astragulus magdelenae var. peirsonii) is a silvery, short-lived perennial plant. A member of the bean and pea family, it can grow to 2.5 feet tall and is notable among milkvetches for its greatly reduced leaves and large fruits. It produces attractive, small purple flowers, generally in March or April, on stalks with 10 to 17 flowers per stalk. Peirson's milkvetch also has the largest seeds of any milkvetch, an important adaptation to its dunes habitat. Large seeds provide a greater reservoir of stored food and enable a seedling to grow a greater distance before emergence and/or depletion of their stored energy. This enables the plant to live on the shifting sands of the Algodones dunes.
In the U.S., the plant is known only on the Algodones Dunes and is highly threatened by off road vehicles. The Center won a precedent setting legal settlement in 2000, closing 49,310 acres of the dunes to ORVs and establishing a planning process to ensure the Peirson's milkvetch is forever protected in the CDCA.