Erect annual or weakly perennial herb up to 1 m tall; stem usually solitary, branching above. Leaves petiolate; blade thin to medium-textured, ovate to ovate-triangular, 40-70(-90) x 35-60(-70) mm, subglabrous to finely pubescent, under-surface with reddish to brownish gland-dots, apex acute, base truncate, margin finely to coarsely crenate-dentate; petiole 20-70 mm long. Inflorescence terminal, paniculate, lax or dense; flowers arranged in opposite and decussate, pedunculate, lax or dense dichasia; peduncle 8-20 mm long; bracts persistent. Calyx 5-7 mm long in fruit, becoming erect and ventricose, subequally 5-toothed. Corolla pale to deep blue (rarely white), 6-7 mm long; tube at first narrow and ascending then sharply decurved about the middle and expanding to the throat; upper lip 2 mm long, lower lip deeply boat-shaped, 4-6 mm long. Stamens free or shortly united at the base, 4-5 mm long.
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