Sulphur lupine is a perennial herb that has a branched stem base. The stems are 40-80 cm tall and are mostly un-branched with silky hairs and short stiff hairs. The leaves are basal and alternate along the stem with 8-13 long leaflets, pointed at the tips and hairy on both surfaces. The flowers are scattered and pea-like at the upper part of the stem. The flower colours range from white to pale yellow.