Medium to tall plant, not aromatic. Stems branched and angled, often reddening and becoming somewhat woody below. Leaves mostly opposite, greyish below usually pinnately lobed with lanceolate divisions. Male Flowerheads greenish tallow 3 to 5 mm in slender spikes. Female flowers inconspicuous below, at the base of the upper leaves. Flower bracts with spiny teeth.

Other Ambrosia have been recorded in Britain, and may turn up

Annual.  Leaves pinnately divided; female phyllaries in fruit with small erect spines near or above the middle

A photo of the whole plant, showing leaves as well as flowers and fruits.

Disturbed ground

August to October

Annual

Not common in Britain.

Uncommonn in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in only 2 of the 617 tetrads.

In the current checklist (Jeeves 2011) it is listed as Alien; casual; disturbed ground; rare.