Perennial, much-branched, subglabrous shrubby herb, 30–100 cm tall, with a pleasant or sometimes acrid aroma and quadrangular branches that are glabrous in the upper parts. Leaves are pinnately and deeply divided, with short lobules that are rarely denticulate. Flowers are slender and lax, borne on terminal spikes composed of distant, two-flowered verticillasters. Bracts are narrowly lanceolate, acuminate, and much smaller than the calyx. Corolla is pale blue, with the tube exserted up to twice the length of the calyx and bent outward below the limb. Flowers have two pairs of unequal-length stamens and style branches flat. Fruits are ovoid nutlets, about 1.5 mm long and 1 mm wide, mucilaginous when wet.