Annual herb, stems erect, 15-45 cm tall, solitary or branched, with glandular hairs. Lower leaves opposite, upper leaves alternate, broadly ovate, oblong, and lanceolate, 2-7.5 cm long, with acute tips, gradually narrowed or semi-clasping at the base, entire, with soft hairs on the leaf surface; without petioles.

Conical corymbs are axillary, with short, soft hairs, and the pedicels are very short; the calyx is tubular, with lanceolate-acuminate lobes, about 2-3 mm long, with soft hairs on the outside, spreading or slightly curved when fruiting; the corolla is urceolate, with a diameter of 1-2 cm, in shades of pale red, deep red, purple, white, pale yellow, etc., with rounded lobes slightly shorter than the corolla tube; the stamens and style are much shorter than the corolla. The capsule is elliptical, about 5 mm long, with a persistent calyx at the base. The seeds are elongate, about 2 mm long, brown.