Spiny shrub, erect or straggling, 90-150 cm tall; stems densely hairy with mixed long ascending buff-coloured or greyish hairs and shorter finer retrorse or spreading hairs, upper internodes usually with interspersed spreading glandular hairs. Leaves sometimes absent at fruiting, broadly ovate or elliptic, 1.2-3 x 0.8-2.2 cm, base rounded to cuneate, apex acute or obtuse, mucronate, surfaces with numerous ascending pale buff or greyish hairs, most dense on veins beneath; lateral veins 3-4 pairs, prominent beneath; petiole 1-7.5 mm long. Inflorescence axillary, numerous in upper portion of branches, each a contracted (1) 2-6-flowered unilateral cyme; primary peduncle 2-7 (9) mm long; bracteoles stoutly spinose, first pair (10)17-31 x 1-2 mm, often disproportionately longer than others in cyme, soon turning straw-coloured, triangular in cross-section, margin entire, pairs persisting at lower nodes as long paired axillary spines. Calyx green or purplish at first with darker venation but soon turning straw-coloured; anterior lobe narrowly oblong, lanceolate or somewhat oblanceolate, 7.5-15 x 2.5-5 mm, base cuneate, margin entire or with minute teeth near apex, apex usually with (1) 2-3 mucronate teeth, surface densely silky-hairy with mixed ascending eglandular and spreading glandular hairs, usually obscuring surface; posterior lobe oblong-lanceolate, 8.5-16.5 mm long, apex acute, stiffly mucronate; lateral lobes linear-lanceolate, 7-14.5 mm long. Corolla (23) 26-31 (36) mm long, blue or mauve, with numerous pale retrorse eglandular hairs and few spreading glandular hairs externally; tube 14.5-21 mm long, cylindrical below attachment point of stamens, widening gradually towards mouth; limb in 2+3 arrangement; abaxial and lateral lobes 8.5-14 x 7.5-13.5 mm; adaxial lobes 3.5-6 x 2.5-4.5 mm. Stamens attached 7-10 mm from base of corolla tube; filaments 11-21 mm long; anthers 3.5-5.5 mm long; lateral staminodes 1.5-2.5 mm long, minutely glandular towards base, antherodes undeveloped or rarely to 0.8 mm long. Ovary with few to numerous pale straight hairs towards apex, extending onto style base; stigma linear, 0.8-1.3 mm long. Capsule 12.5-16.5 mm long, with few pale hairs at apex. Seeds c.5 x 5 mm.
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Undershrub, up to 1 m high, pilose. Flowers in 1-6-flowered unilateral cyme. Bracts spinose, 15-35 mm long, solid, pubescent. Corolla somewhat 2-lobed, 2 upper lobes short, ± a quarter as long as 3 lower lobes. Flowers blue.