Kew Gardens is building an army of volunteers to launch an attack on a foreign weed which is threatening the survival of the British bluebell.
Bluebells are deprived of their light source
The team at the Royal Botanical Gardens in Richmond, south west London, will be helped by 300 people as they dig up the yellow-flowered Perfoliate Alexanders.
Experts say the invasive plant must be brought under control as it deprives bluebells of their light source.
Volunteers will work on the one-day project in May.
Carpet of bluebells
The spring flowers, which are native to southern Europe and parts of Africa and Asia, are taking over about 40 acres of woodland area at Kew.
They grow to about 1.5 metres and have large flowers which deprive bluebells of their essential light source.
Simon Cole, manager of natural areas at Kew, said: "They are really a beautiful plant but they have begun to take over."
He said they did not plan to eradicate the plant but to bring them under control to ensure a good carpet of bluebells.
The event on 22 May is part of Environment Month and Year of the Volunteer.