Biennial wormwood

Artemisia biennis, commonly called biennial wormwood, is an annual or biennial herb in the Asteraceae family, native to western North America and now widely naturalised across temperate regions. It typically grows 30 to 200 cm tall with a stout, erect, single stem that is glabrous and often reddish at the base, branching freely above. The leaves are deeply pinnately divided into narrow, sharply toothed lobes, bright green and aromatic when crushed, though less strongly scented than many other wormwoods. The inflorescence is a slender leafy panicle of numerous small, sessile, greenish-yellow flower heads arranged along the upper stems and in the leaf axils. Each head contains tiny disk florets only, with no ray florets. Flowering and fruiting occur from late summer to autumn. The achenes are minute and glabrous, lacking a pappus. It typically colonises moist, disturbed ground such as ditches, riverbanks, fields and roadsides.