Erect, annual herb, 7-28 cm tall. Cauline leaves 5-10 x 3-9 mm, ovate - broadly ovate, rarely elliptic, 4-5 lobed, with truncate base; lobes acute-acuminate, longer than broad, upper antrorse, lower patent (5-7 x 3-4 mm, ovate rarely elliptic, 4-lobed, lobes acute in aestival and 7.5-10 x 4.5-9 mm, broadly ovate, 5-lobed, lobes acuminate in autumnal form). Racemes lax. Floral leaves similar to cauline leaves, but lateral lobes acuminate-aristulate; 6-8 x 5-6 mm (lobes acuminate in aestival and aristulate in autumnal form). Flower 7-9 mm long; pedicels c. 1 mm long. Calyx 4-5 mm long; lobes 2 x 0.5 mm, equal; tube 2-3 mm long. Corolla white, throat yellow, dorsally 7-8 mm long; tube 4-4.5 mm long, externally glabrous or sparsely pubescent on the upper lip. Upper lip 3-4 mm long. Lower lip 3-5 mm long; lobes oblong, obcordate, erose-deeply notched, middle lobe largest, 2-3.5 x 1.5-2 mm, left and right lobes unequal, left lobe 2-3 x 1-2.5 mm, right lobe 1.5-3 x 1-2 mm. Two anthers with equal and two with unequal awns, densely hairy; hairs short equalling the longer awn. Capsule 5-6 x 2-2.5 mm, oblong, retuse-emarginate, shorter than the calyces, ciliate at the upper part; cilia soft. Seeds 6-10 per capsule, (6-7 seeds in aestival and 8-10 seeds in autumnal form), oblong, obtuse.