skip to main |
skip to sidebar
Marsh thistle Cirsium palustre flowers are generally deep purple (bottom photo) but, wherever you go in the North Pennines, you begin to notice white-flowered plants (top photo) once you climb more than about 1000 feet above sea level. As you go higher, the white flowered forms become more prevalent. Why? One suggestion, put forward by Dave Mogford at Oxford University back in 1974, was that white-flowered forms tend to attract more bumblebee pollinators, so it pays to be white at higher altitudes, where bumblebees are fewer. If that's the case, why aren't there white-flowered populations of other thistle species at higher altitudes? There’s scope for amateur naturalists to make some observations to check out this explanation....................
Marsh thistle Cirsium palustre flowers are generally deep purple (bottom photo) but, wherever you go in the North Pennines, you begin to notice white-flowered plants (top photo) once you climb more than about 1000 feet above sea level. As you go higher, the white flowered forms become more prevalent. Why? One suggestion, put forward by Dave Mogford at Oxford University back in 1974, was that white-flowered forms tend to attract more bumblebee pollinators, so it pays to be white at higher altitudes, where bumblebees are fewer. If that's the case, why aren't there white-flowered populations of other thistle species at higher altitudes? There’s scope for amateur naturalists to make some observations to check out this explanation.................... 
Posts
