Pictorial guide to the flora of the British Isles

Home ⟩ Pictorial Guide ⟩ Asteraceae / Compositae ⟩ Ambrosia artemisiifolia / ragweed

Ambrosia artemisiifolia L.

ragweed (Asteraceae / Compositae)

 SpreadBias within British IslesDirection of bias
RestrictedModerate tendencySE
Plant Atlas 2020
BSBI Distribution Map

Ambrosia artemisiifolia is a North American species that is increasingly frequent in disturbed habitats, especially in the south-east.

Oxford (VC23: Oxfordshire); 2023-09-11

 ragweed / Ambrosia artemisiifolia: _Ambrosia artemisiifolia_ is a North American species that is increasingly frequent in disturbed habitats, especially in the south-east.

As its scientific name suggests, the leaves of Ambrosia artemisiifolia are repeatedly pinnately lobed, like those of some Artemisia species.

Oxford (VC23: Oxfordshire); 2023-09-11

 ragweed / Ambrosia artemisiifolia: As its scientific name suggests, the leaves of _Ambrosia artemisiifolia_ are repeatedly pinnately lobed, like those of some _Artemisia_ species.

The inflorescences of Ambrosia artemisiifolia are peculiar for a composite; male heads are arranged in tall spikes and each droop downwards.

Oxford (VC23: Oxfordshire); 2023-09-11

 ragweed / Ambrosia artemisiifolia: The inflorescences of _Ambrosia artemisiifolia_ are peculiar for a composite; male heads are arranged in tall spikes and each droop downwards.

The female capitula are lower down, consist of only 1 or 2 flowers, and point their wind-pollinated stigmas upwards.

Oxford (VC23: Oxfordshire); 2023-09-11

 ragweed / Ambrosia artemisiifolia: The female capitula are lower down, consist of only 1 or 2 flowers, and point their wind-pollinated stigmas upwards.

All images copyright © Christopher J. Dixon unless otherwise indicated.

L-R: Bidens tripartita, Melilotus officinalis, Mimulus guttatus, Thalictrum flavum, Ranunculus peltatus, Anchusa arvensis, Malva alcea, Lolium perenne