Ragweed - Ambrosia artemisiifolia

Description

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.

Similar Species

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

Identification difficulty
ID guidance

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

Recording advice

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

Habitat

Disturbed ground

When to see it

August to October

Life History

Annual

UK Status

Not common in Britain.

VC55 Status

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.

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map