Weekly Witter: Battle of Britain’s bluebells

The Natural History Museum online Bluebell Survey

Are British bluebells under threat?

Are British bluebells under threat?

Since 2006 scientists at the NHM have been asking the public to look more closely at one of Britain’s best loved plants and report their data online. Initially driven by the desire to understand whether this iconic species was indeed threatened by an invasive alien, the Spanish Bluebell (Hyacinthoides hispanica), our work soon became a quest to understand just what the plant we thought of as the Spanish Bluebell was and where it had come from, before we could begin to understand what we were seeing in the British countryside. Molecular work demonstrated that the Spanish and English Bluebells were very similar, indeed there was as much genetic variation between the populations of Spanish bluebell isolated on the different mountain ranges across Iberia as there was between it and our native plant. Study of the narrow zone where they meet in northern central Spain revealed a confusing mix, just like we can find in urban areas in Britain. Only geographical isolation has kept them apart and distinct as there is no apparent barrier to breeding between them. As a consequence our horticultural endeavours have in less than 250 years done much to undo the last 10,000 plus years of isolation and evolution!

“So were the doom merchants justified in their apocalyptic statements?”

It became clear that the plant which had become associated in British botanist’s minds as typical Spanish Bluebell was actually a triploid, the like of which our criss-crossing of Iberia had failed to find. It is likely that if this didn’t arise early in cultivation it was of a selected form, picked out for its robustness and vigour (and not for its charm!) not subsequently found in the wild. It was also obvious that over time plants from different parts of Iberia had found their way to British gardens and because of the variability in the species we could determine that our problem plants might better be called Portugese rather than Spanish Bluebells!

“Plants abandoned on roadsides adjacent to major native populations may inexorably spread alien genes…”

So were the doom merchants justified in their apocalyptic statements? To an extent yes – with no barrier between them interbreeding will occur wherever the taxa meet, and our gardens, wherever they be across the country, the British public had shown us were full of hybrid plants. It was also clear that the major ancient woodland areas supporting the world’s largest stands of Hyacinthoides non-scripta were, as yet, largely unsullied and untainted by the alien. In areas around our major towns and cities, where ancient woodland habitats are small and fragmented and in close proximity to gardens and fly-tippers, populations were mixed. The message thus then became one of educating the public not to dispose of unwanted garden plants irresponsibly. Plants abandoned on roadsides adjacent to major native populations may inexorably spread alien genes although encouragingly it seems that most pollinator movements may be going the other way, from our native plants to the invaders.

Having better established the distribution of alien plants (or their genes) within the British Isles we then decided that our survey may provide us with an excellent opportunity to build a more robust data set looking at the phenology of flowering in this species, which may help provide evidence on the existence and effects of climate change. To do this meaningfully requires very many years’ worth of data (not least to counter natural yearly fluctuations such as we see now) and as many members of the public contributing as possible, hopefully with the same plants recorded year after year. Responses to the survey peaked late in the flowering period last year following my appearance on the BBC’s One Show and we hope that all those people who contributed then will do so again this year. Last year our first records were made early in the first week of March, some five weeks or more ahead of our first this year and most plants I see even in the cities heat are still more than a fortnight from flowering.

A stunning bluebell display at Fountains Abbey.

A stunning bluebell display at Fountains Abbey.

By carefully identifying plants using our online guidance, with the fallback of being able to send images to me here at the museum enquiries team (ias2@nhm.ac.uk) to help with this, it will be possible to document whether hybrid and Spanish plants do flower earlier so that we can discount this as one cause of change in flowering time and behaviour.

  • Fred Rumsey– Angela Marmont Centre for UK Biodiversity, NHM
  • Experts at the National Trust believe that due to the late spring, British bluebells are still weeks away from flowering. Read more here.
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