A highly variable shrub. Some forms are many-branched and very low-growing; others are small, erect shrubs to ~0.5 metres. This may be genetically or environmentally controlled. Leaves are small, narrow and linear or roughly oblong, with a grey tinge and few or no hairs. They are often held close to the stem. Flowers are yellow with red markings. Pods are pale brown, containing 1 or 2 dark seeds. These shed swiftly.