Artemisia biennis aka Biennial Wormwood

Artemisia biennis has two common names: biennial wormwood and slender mugwort. It belongs to Asteraceae, the daisy family. Its native range spans Alaska and western North America. Records list western Canada and several western US states. It grows in temperate zones, where the climate is mild. It is not native to Britain or Ireland. This short-lived herb can live for one or two years.

Plants often reach 1–2.6 feet [0.3–0.8 metres] tall. One garden account gives a height of 3.3 feet [1 metre]. That account gives a spread of 1.6 feet [0.5 metres]. A few plants reach about 4.9 feet [1.5 metres]. Plants grow fast and often form one stem without branches. This upright herb has scented leaves with fine cuts. Wind carries its pollen. Each flower has both male and female organs. The plant makes many small seeds, which help it spread.

In the wild, it grows on open sites and disturbed soil. These sites include clearings, burned ground, roadsides, and waste ground. It grows in full sun and takes part shade. Sand and loam suit it if water drains well. It also grows in poor soil with sand or gravel. Its stated needs call for neutral to slightly alkaline soil. It takes dry or moist soil. Once rooted and settled, it can cope with drought. For best growth, it needs moist soil in summer. PFAF lists USDA zones 3–8. But PFAF doubts how well it withstands Britain's cold.

Garden records show this species growing in beds. It spreads well by seed and can become a weed. Its seeds can sprout where something has disturbed the ground. Sow seeds on the surface in spring, under glass. Keep the compost moist as the young plants grow. Move them outdoors in early summer. You can also sow straight into the ground in late spring. The supplied evidence names no pests or diseases for this plant.

Records describe use of the seeds as food. Their small size makes them slow to gather. Goshiute people gathered them for flour and porridge. PFAF says to use seeds in modest amounts. It gives them a low food value. PFAF says other parts are not fit to eat. They taste bitter and contain toxic compounds. Records describe past use to treat cramps and wounds. They also describe use against worms in the gut. These records show use, not proof of safety or benefit. PFAF reports no known cases of poisoning from this species.