Erect, ± hairy annual herb to c. 80 cm high, but plants often only a few cm high in impoverished conditions. Stem angular, ± hairy when young, red, especially towards base. Petiole to c. 7 cm long, often reddish, usually hairy. Lamina extremely variable according to habitat, 2-11 × 1-7 cm (smaller in infl. and very depauperate plants), ovate or rhombic-ovate, usually glabrate beneath and becoming glabrous above; base narrow-cuneate to attenuate; apex obtuse, sometimes mucronate. Panicles green, with elongated main spike to c. 25 cm long at fruiting, with shorter spikes in axils of uppermost lvs, the lvs sometimes very reduced. Longer bracteoles 4-8 mm long, ovate, with long subulate green tip; shorter bracteoles similar. Fls 4-5-merous; tepals very unequal, especially in ♀ fls; ♀ fls with 1-2 longer and 3 shorter tepals, the longer 2.5-3-(4) mm, ± oblong, keeled, gradually tapering to the sharply acute or short-acuminate apex. Fr. subglobose, circumscissile, usually with prominent neck, not exceeding tepals except for the 3 persistent stigmas. Seed 1-1.5 mm diam., lenticular, dark brown or black.