Small herbaceous shrub, up to 1.3 m tall, sometimes scrambling. Stems covered in short and coarse yellowish hairs. Leaves opposite, ovate or elliptic, 4-10 cm long, densely covered in pale grey stellate hairs when young, becoming more or less hairless when older. Flowers in 2-7-flowered axillary clusters. Bracteoles linear-lanceolate, in unequal pairs, largest 10-23 mm long; margin with widely spaced teeth and a spiny apex. Calyx lobes broadly ovate, largest 13-19 mm long, translucent with conspicuous reddish-brown veining; margin with coarse spiny teeth. Corolla 27-37 mm long, blue-mauve with a white tube, hairy on the outside. Capsule 11-13.5 mm long, mostly hairless.