An erect shrub up to 1.2 m, with subterete to 4-angled, ± viscous pubescent twigs. Leaves on 2.5-8.5 cm long, apically winged hairy petiole, lamina ovate, 8-16 x 4.5-8 cm, puberulent on both sides to glabrescent, basally cordate or ± rounded, serrate, acuminate. Flowers dark-blue, c. 2 cm across, in lax, glandular-pubescent paniculate spikes; bracts narrowly lanceolate-oblong, shorter than calyx, early caducous; bracteoles narrowly oblong, 4-5 mm long, caducous. Calyx lobes 5, unequal, ligulate, 8-12 mm long, glandular pubescent, obtuse, enlarged and accrescent in fruit, one much larger than the rest. 3-4 cm long, tube cylindrical below, as long as calyx, curved above, within, limb lobes patent. Staminal filaments dilated, glabrous. Ovary hairy, style sparsely hairy with linear stigma. Capsule narrowly elliptic-oblong, 1.5-1.7 cm long, glandular-pubescent to glabrescent, 4-seeded. Seeds ovate, c. 3 mm long, hairy.