A much-branched shrublet, up to 400 mm high. The stems arising from a woody rootstock. Younger stems are covered with hairs, whereas the older stems become glabrous. The leaves are ovate or elliptic-ovate, blueish green and the leaf margins are thickened and wavy with spines and sometimes white. The petiole is short and the apex (leaf tip) ends in a spine.

The flowers are solitary or clustered in lateral cymes (a type of inflorescence), with 1–10 flowers in alternate or opposite axils. The flower colour is mauve, white, cream-coloured, lilac, blue or purple. The corolla (flower petals) is 2-lipped, upper lip 4-lobed, lower lip 1-lobed. The corolla tube is cylindrical.

Each flower is subtended by modified leaves called the calyx lobes. The outer calyx lobes are elliptic, glabrous and with or without the purplish tinge on the veins. The calyx lobe margins are spine-toothed, the apex tapered and ending in a spine. The secondary bracts are called the bracteoles. The bracteole lamina is developed or spinous, with a prominent midrib and margins, with a few scattered teeth, the apex tapered into a sharp point.

The seed capsules are elliptic and tapering to a point. There are 4, hairy seeds per capsule.

This variety can be distinguised from var. rigida by its ovate leaves and conspicuously spiny, sinuate leaf margins, with the spines evenly distributed. The leaves of var. rigida are linear, and the margins are undulate, and have small spines or none.