Coast Swainson-pea is one of the spectacular wildflower plants of the sand dunes with its deep, rich purple pea-shaped flowers on display from mid-winter to early summer. It is a sprawling perennial herb that can occasionally be short-lived insitu but is able to survive from one generation to the next through copious and long-lived seed production. Its unique connection to coastal sand dunes makes it hard to adapt to garden situations where heavier soils and overly wet soil conditions quickly causes its demise.
Leaflets are elliptic in shape and the tips notched. They are evenly arranged in pairs along leaf stems.
Flowers are held upright above the foliage; sometimes in large displays. Flowering is extended by summer rains. Oblong, seedpods appear during flowering becoming dark at maturity.