Erect annual herb, up to c. 1.2 m tall. Stems longitudinally ribbed and pubescent. Leaves rhombic-ovate, up to 7 × 5 cm, 5-veined from the base, hairless to finely velvety on both surfaces; margin toothed except near the base. Flowers in axillary spikes, unisexual on the same inflorescence. Female flowers below, held in shallowly cup-shaped bracts with toothed margins; male flowers above, very small, yellowish-green. Fruit 1.5 × 2 mm, 3-lobed, tuberculate, pubescent. 

 Note: this species is part of a closely related group, including A. crenata and A. segetalis.