A herbaceous perennial plant, a species of the genus Linseed. The root is taproot or with long creeping shoots.
The stem is 30-60 cm tall, erect, simple or branched, densely deciduous.
The leaves are linear-lanceolate or linear, pointed, with one, rarely three veins, wrapped at the edges, glabrous, 2-5 cm long and 2-4 mm wide, upper linear.
The flowers are collected in thick long apical brushes, 5-15 cm long. Axes, pedicels and, less often, calyx are covered with glandular hairs, very rarely almost naked. Pedicels 2-8 mm long, bracts lanceolate, exceeding pedicels or equal to them.
Calyx with lanceolate lobes, finely pointed, mostly glabrous or with sparse hairs on the outer side, glabrous inside, 3 mm long, 2 mm wide. The corolla is yellow, with a bright orange bulge on the lower lip, 15-18 mm long (without a spur), the upper lip is much larger than the lower one, with a recess 2.5—3 mm deep, the lower lip with rounded lobes, 5 mm wide, the middle one is narrower, the spur is broadly conical, curved, 12-15 mm long, 2.5—3 mm wide at the base, bright yellow. Blooms in June—August.