BRITAIN'S favourite flower is enjoying its annual season in bloom but its survival is threatened by a Spanish invader.
The native British bluebell, Hyacinthoides non-scripta, has been found in the UK since the Ice Age. But its future in the wild, where it carpets woodland with a blaze of colour every spring, is threatened by its Spanish cousin, Hyacinthoides hispanica.
This is an introduced species of plant which cross-breeds with the native bluebell. But because the Spanish species and the resulting offspring have more dominant genes, the native bluebell traits quickly disappear.
That could mean no more of the deeper blue, nodding bell-shaped blooms arching delicately away from a dark foliage. Instead the foliage becomes paler and wider, and the flowers more open on an upright stem that has lost its graceful arch.
"If you took a leisurely walk through a bluebell wood you would not necessarily notice the difference but once you know about it, it's unmistakeable," said Wolfgang Bopp, curator of the National Botanic Garden of Wales.
The Garden is encouraging visitors to join thousands of volunteers taking part in a survey this spring to determine to what extent the Spanish invasion has taken root.
The survey is organised by Plantlife International and the Botanical Society of the British Isles. It is called Bluebells for Britain and supported by the Heritage Lottery Fund - and will be used to assess the health of the plant in the face of threats to its future. Like many wild flowers, the bluebell is vulnerable to nutrient pollution and habitat destruction from modern farming, but is also put at risk by people illegally collecting armfuls of the flowers.
Although currently widespread in Britain, the bluebell is actually under threat. Up to 50% of the world's population is found in Britain, which gives the UK an international obligation to protect the species.
Martin Harper, Plantlife International's conservation director, said, "We simply must do all we can to ensure that the bluebell remains safe in the wild - and this survey is the first step in achieving that aim."
* To take part in the survey, log on to www.plantlife.org
.uk, or ring 020 7808 0118 for a full survey pack.