Himalayan balsam, an invader that thrives on air pollution, is crowding out British plants, say experts.
The ‘thuggish’ plant, introduced to the UK in 1839, can grow as tall as 10ft and fling seeds up to 22ft away.
It absorbs nitrogen produced by diesel cars and grows incredibly fast – smothering other plants as it spreads.
Conservation charity Plantlife raised the alarm about Himalayan balsam in a report from the National Plant Monitoring Scheme (NPMS) which surveys habitats for wildflowers.
Experts are warning that Himalayan balsam is posing a threat to British plants as it overcrowds them while it spreads
The plant can grow as tall as 10ft and can fling seeds up to 22ft away. It absorbs nitrogen from diesel cars. Conservation charity Plantlife raised the alarm about Himalayan balsam in a report from the National Plant Monitoring Scheme (NPMS) which surveys habitats for wildflowers
Dr Trevor Dines, of Plantlife, said: ‘It’s a very high nitrogen-demanding species, and it’s a great big thuggish thing and it can flatten vegetation around it.’
The species, which forms dense thickets to shade out other vegetation, was more frequently recorded in woodlands than native plants such as wild garlic, woodruff and bugle.
The latest NPMS found just five species – nettles, brambles, cleavers, hogweed and cow parsley – now account for almost half of all plant sightings in woods.
The prevalence of these species is also thought to stem from nitrogen pollution, which benefits plants that thrive in nutrient-rich conditions.
The much-loved bluebell is still the most frequently seen wildflower, the survey found. But once-common native flowers such as early dog-violets and marsh-marigolds, which prefer infertile soils, appear to be struggling in competition with nettles and brambles.
The NPMS relies on hundreds of volunteers who take part in the annual survey – the largest of its kind – from March to September.
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