Erect, annual herb, 8-25 cm tall. Cauline leaves 6-10 x 3-6 mm, elliptic-ovate rarely broadly ovate, (3-) 4-5 lobed, with truncate base; lobes acute-acuminate, longer than broad, upper antrorse, lower patent 6-8 x 3-4 mm, elliptic, 4-lobed, lobes acute in aestival and 8.5-10 x 4.5-6 mm, ovate rarely broadly ovate, (5-lobed, lobes acuminate in autumnal form). Racemes lax. Floral leaves similar to cauline leaves, 4.5-10 x 3-8 mm. Flowers 6-10 mm long. Pedicels c. 1 mm long. Calyx 3-5 mm long; lobes 1.5-3 x 0.5-1 mm, unequal; tube 1.5-3 mm long. Corolla white, lower lip yellow-light purple, upper lip violet, dorsally 5.5-9 mm long; tube 2-6 mm long, externally pubescent especially on the upper lip. Upper lip 2-4 mm long. Lower lip 3-5 mm long; lobes oblong-obovate, rarely spathulate, obcordate, erose-deeply notched, middle lobe largest 1.5-4 x 1-3 mm. Left and right lobes unequal, left lobe 1.5-3 x 1-2.5 mm, right lobe 1-3 x 1-2.5 mm. Two anthers with equal and two with unequal awns, densely hairy; hairs short equalling the longer awn. Capsule 4.5-7 x 1.5-3 mm (c. 4.5 x 1.5 mm in aestival and 5-7 x 2-3 mm in autumnal form), oblong, retuse, ciliate at the upper part only or all over; cilia soft. Seeds 4-14 per capsule (4-7 seeds in aestival and 8-14 seeds in autumnal form), oblong, obtuse.