Plants to 1(–1.5) m, erect and widely branched, or sometimes ± prostrate; lvs green especially on the upper side, the principal ones 4–12 cm, lanceolate to rhombic-hastate with a cuneate base; infls numerous, interrupted-spiciform, more continuous upwards, leafy-bracteate only near the base; fruiting bracteoles thin, foliaceous, joined near the base or almost to the middle, obscurely veined or only the midvein prominent, mostly 3–7 mm, ovate to more often rhombic-triangular or triangular-hastate, acute to acuminate, entire or with 1 or 2 short lateral teeth, smooth or with irregular appendages on the back; seeds dimorphic, some brown, 2.5–3.5 mm wide, others black, smaller, 1.2–3 mm wide; radicle ± inferior; mainly or wholly tetraploid on x=9. Widespread ruderal weed, only casually maritime, intr. from Eurasia. (A. acadiensis)
An annual herb. It grows 30 cm to 1.5 m tall. The leaves are alternate. The leaves are sword shaped and 3-14 cm long. The lower leaves can be more broad with a wedge shaped base that tapers into a short leaf stalk. The upper leaves do not have a leaf stalk. The seeds are 1.2-1.5 mm across.
Sprawling, grey-mealy annual to 50 cm. Leaves lanceolate to rhomboid, coarsely toothed to lobed below, glabrescent above. Flowers clustered in elongate spikes, whitish; fruiting bracts rhomboid, often with small horns, to 2 mm long.