The plant is an erect annual herb, 20-150 cm tall (in tall plants sometimes the branches straggling), very variable, reproducing by seeds. Main root pivotant. Stems square, glabrous or minutely hairy, green or with brown strips. Dark green, opposite leaves on stems and branches, 4-20 cm long, up to 6 cm wide, the lower leaves simple, ovate and serrate, the upper leaves trifoliolate or imparipinnate with 2-3 pairs of pinnae and a single terminal leaflet. Petioles are 2-5 cm long.