Sturdy herb, stongly aromatic. Stems up to 1 m, usually much-branched, quadrangular, with long spreading white eglandular hairs, ± hirsute. Leaves ovate to broadly ovate, c. 3-7 x 2-4 cm, rounded or cordate, apically acute, finely serrulate, pubescent or tomentose, gland-dotted on abaxial surface; petiole up to 33 cm. Flowers 2-6 in axils of middle and upper leaves, borne on up to 12 mm peduncles. Bracts very small, setaceous. Calyx campanulate 3-4 mm in flower enlarging to 8-10 mm in fruit and stongly ribbed; tube distinctly truncate apically fringed with white villous hairs; teeth subequal, erect, 2-3 mm, subulate; indumentum of spreading eglandular and capitate glandular hairs. Corolla 5-7 mm, blue, soon deciduous; 2 upper and 3 lower oblong lobes of similar size. Staminal filaments white-hairy. Nutlets usually 2, 3.5 x 2.2 mm, strongly flattened laterally, apically emarginate, with a white V-shaped attachment scar, brown, finely papillose, densely white-mucilaginous on wetting.

Type: [? Jamaica] LINN 737/6 (microfiche!).

Distribution: Native of tropical America and naturalized in almost all tropical or subtropical countries.

The various medicinal uses of this species are listed in the Wealth of India (1.c.); in India, an infusion of the leaves is sometimes taken as a beverage.