Biennial, rarely perennating, robust, 30-120 cm tall, glabrous to hirsute, subglacous, erect, with much branched inflorescence above. Basal leaves rosulate, oblanceolate, short-stalked, 5-15 cm long, 1-3 cm broad, very variable in size and often much larger in cultivated plants, entire or subdentate; cauline leaves 10-80 mm long, 5-25 mm broad, linear-lanceolate, auricled at base, amplexicaul, entire; uppermost much smaller. Racemes 30-80-flowered, panicled, ebracteate, increasing up to 10 (-15) cm in fruit. Flowers 4-5 mm across, yellow; pedicel 5-10 mm long in fruit, filiform, + deflexed. Sepals 2-2.5 mm long, yellowish-green. Petals 3-4.5 (-5) mm long, 1.5-2 mm broad, aobovte cuneate towards base, apex rounded. Stamens c. 2 : 2.5 mm long. Siliculae very variable in size, 10-20 mm long, 2.5-5 mm broad, oblong, tapering towards the base, with truncate to rounded apex, often somewhat broad in the middle (at locule), glabrous to puberulent; locule shorter than the apical portion of the wing; seed 3-4 mm long, 1 mm broad, oblong ellipsoid, brown.

A very polymorphic species and highly variable. Several subspecies and varieties have been recognized under it. Davis (l.c.) recognized 3 subspecies under it for Turkey. Hedge (in Rech. f.,l.c. 84) considered Isatis koelzii Rech.f. as a separate species from Isatis tinctoria, on the basis of short oblong fruits (c. 15 mm long), rounded at both ends. Fruit size is not exclusive for it and the apex is often slightly rounded in Isatis tinctoria; fruit base is always cuneate and tapering, and it is not clear as to what Hedge actually meant by rounded basal end. However, Isatis koelzii with small looking fruits and small size of plants in our area, does not justify more than a subspecific rank under Isatis tinctoria. The type race, i.e. subsp. tinctoria, is primarily an European, N. and N. E. Asian taxon, while our plants and that of Afghanistan fall under subsp. koelzii.