A Kind of Blue: 30th April
Spanish, English and hybrid bluebells. What's out there?
A Kind of Blue
Just now, bluebells are all over our ancent woodlands and green spaces. So I spoke to staff at Sheffield and Rotherham Wildlife Trust (SRWT) about what’s actually out there shimmering on our woodland floors.
How much has the Spanish Bluebell infiltrated the populations of our own native Common or British Bluebell? A few years ago, the Trust carried out woodland transects checking the extent of bluebell cover during the flowering season in April and May, and how the Spanish variety had spread.
The British or Common Bluebell is an important native flower: we love it, and because it blooms early, insects like woodland butterflies, bees and hoverflies love it too, so it helps retain biodiversity. It’s estimated that at least 50% of the world’s population of the Common Bluebell is in Britain.
Then there are Spanish Bluebells, which have been imported as garden plants since Victorian times. Non-native garden bluebells often ‘jump the garden wall’ into our woodlands, where their close relative, the Common Bluebell, has been doing fine without them for thousands of years.
The two species can then intermingle into hybrids, which can be white, pink and many shades of blue. SRWT have a handy spotters guide to the differences here. (See picture below).
The advice from SRWT to try and reduce the spread of Spanish and hybrid varieties and retain the Common Bluebell is fairly simple:
Buy British - make sure any new bluebell planting is of the native variety, usually labelled as British or UK Bluebell, but note some bulbs are incorrectly labelled. If possible, ask advice or check the country of origin, and if the bulbs are from Europe they’ll most likely be Spanish plants. (Readers with advice of reputable British / Common Bluebell sources please comment below.)
Remove Invasive Bluebells - if you do have Spanish or hybrid Bluebells in your garden, could you take them out and replace them with native British Bluebells?
Compost, Don’t Dump - if you do decide to uproot Spanish or hybrid plants, dig up the whole plant, including the bulb and leaves, then leave it to dry out. Don’t throw it in the green waste bin, or chuck it into the woods or over the garden wall as this could allow the plants to spread to other areas. Instead, tie them in a black plastic bag and leave them for a year to rot down.
Don’t Trample or Pick - picking British Bluebells can destroy the plant if the root is damaged or taken out, and trampling over them can damage the plant’s chances of surving for another season.
The SRWT survey found bluebells of various types across the city. (See the map, where the blue circles indicate the bluebell density at that site, and any pink showing the existence of Spanish or hybrid varieties.)
The report concluded that gardens were the primary source of non-native bluebells in Sheffield’s woodlands, often through the dumping of garden waste, literally over the fence or wall in the case of some sites in Ecclesall Woods.
However, the project also found that non-native bluebells were usually on the outskirts of woodlands, not in the centre, with records mostly close to obvious patches of dumped garden waste, gardens containing non-native bluebells, or where there was fly tipping.
SRWT learned from recent studies that in fact, the native bluebell may be less threatened than originally thought.
Botanist Dr Fred Rumsay from the Natural History Museum reported that the genetic vigour of the British Bluebell may overcome the Spanish interloper and its hybrid descendants, not least since some modern garden varieties have been cross bred sufficiently to be largely infertile.
“Genetic drift could be taking place from native to non-native populations when the latter have been introduced to the wild. Native populations genetically submerge the limited non-native pool,” he said.
Further research is needed, and in the meantime please follow the native bluebell protection advice, says Nicky Rivers from SRWT.
Her own favourite bluebell woods are of course, Woolley Wood, and also the woodlands of the Moss Valley, which as old, hilly, undisturbed sites tend to feature a great display over the next few weeks.
“A native bluebell wood is a delight to the senses,” she says. “There’s that vibrancy of the purple blue colour, and native bluebells also have a sweet smell, I think, whereas Spanish Bluebells barely smell at all. Now’s the time to take your kids out to get the sweet smell of the woodlands in spring.”
And then she throws in a small edge of caution before we all get too intoxicated by fragrant British Bluebells. There are some ecologists, she says, who say that carpets of bluebells may not have been natural in British prehistory.
Our woodlands would once have been home to bison, and wild boar and any number of larger herbivores who dug up and rolled around on the woodland floor. In those days, instead of bluebell carpets, we’d more likely have patches of bluebells among lots of other flowers, which may have thrived better without so much ground-hugging bluebell foliage to contend with.
So when you visit Woolley Wood or Ecclesall or Greno or Ladies Spring Wood or Bowden Housteads, or any of our other bluebell woods in the next few weeks, maybe cast your mind back a few thousand years, and wonder if those sweet smelling spring woodlands would be even more spectacular with a bison or wild boar watching you through the undergrowth.
Do add your comments below - where do you think are the best bluebells in Sheffield?
Great article, and quite reassuring to read that the native bluebells might be more up to holding their own against the Spanish and hybrids than previously thought. And the map is fascinating - but why isn't Ecclesall Woods shown?