Ragweed - Ambrosia artemisiifolia
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Species Description
Widespread but infrequent casual (often birdseed alien) throughout the UK. Habitat includes: margins of lakes and reservoirs, tips, wasteland etc.
Stace 4:
Ambrosia artemisiifolia L. - Ragweed.
Annual; stems erect, to 1m; leaves deeply pinnately divided, the larger ones with the primary lobes divided again, green, appressed-hairy but often sparsely so; (2n=36). Neophyte-casual; waste ground and tips from several sources, including birdseed and oilseed; fairly frequent in Britain North to Central Scotland, Channel Isles, Isle of Man, sometimes semi-naturalised; North America.
Key:
- Leaves pinnately divided nearly to base, the upper ones alternate; leaf lobes <1cm wide
- Annual; female phyllaries in fruit with small erect spines near or above the middle