Erect, annual herb, 10-30 cm tall. Cauline leaves 5-12 x 3-8.5 mm, elliptic-ovate, rarely broadly ovate, 3-4 lobed, with truncate base; lobes acute-acuminate, longer than broad or as long as broad, upper antrorse, lower patent (5-7 x 3-6 mm, elliptic, 3-lobed, lobes acute as long as broad in aestival and 7.5-12 x 6.5-8.5 mm, ovate or broadly ovate, 4-lobed, lobes acuminate, longer than braod in autumnal form). Racemes lax. Floral leaves 4.5-14 x 3.5-14 mm, broadly ovate, 4-6 lobed, with truncate base; lobes acuminate, longer than broad or as long as broad, upper antrorse, lower patent (4.5-8 x 3.5-7 mm, 4-lobed, as long as broad in aestival and 8.5-14 mm, 5-6 lobed, lobes longer than broad in autumnal form). Flowers 6.5-9 mm long; pedicels 0.5-1 mm long. Calyx 4-6 mm long; lobes 1.5-3 x 0.5-1 mm, usually unequal, rarely equal; tube 2-3.5 mm long. Corolla white with yellow throat, dorsally 6-9 mm long; tube 2-6 mm long. Upper lip 2.5-5 mm long, externally sparsely pubescent. Lower lip 3-5 mm long; lobes oblong-obovate, obcordate, erose-deeply notched, middle lobe largest 2-4 x 1.5-3 mm, left and right lobes equal, rarely unequal, left lobe 1.5-3.5 x 1.5-3 mm, right lobe 1.5-3.5 x 1.5-3 mm. Two anthers with equal and two with unequal awns; hairs short equalling the longer awn. Capsule 4-7 x 2-4 mm (c. 4 x 2 mm in aestival and 4.5-7 x 2.5-4 mm in autumnal form), oblong, retuse shorter than the calyces, ciliate at the upper part; cilia soft. Seeds 10-11 per capsule (c. 10 seeds in aestival and c. 11 seeds in autumnal form), oblong, obtuse.