Friday, June 24, 2011

A short epistle on thistles


It is a truth universally acknowledged that whenever I kneel down to take a photograph my knee finds a thistle.

True thistles in the UK fall into 2 families: Cirsium and Carduus (Carduus is Latin for 'thistle'). The Carduus genus has 3 representatives in the UK; Carduus tenuiflorus, Carduus nutans & Carduus crispus. I saw all 3 (I trust I have my id correct!) growing within metres of each other at Folkestone Downs in early June. Jolly convenient as they were right near to where I parked the car.

Carduus tenuiflorus Slender thistle

Slender thistle at Dungeness
Slender thistle on Folkestone Downs

This is a slimline thistle, with pale, grey-green stems and leaves. It's flower heads are small, clustered and a lovely pale pinky-purple. Quite distinctive. It tends to prefer growing near the sea.

Carduus nutans Musk or nodding thistle

Musk (nodding) thistle on road, Folkestone Downs

Musk thistle is very distinctive with its large, nodding heads. It's a tall, robust looking thistle with spiny, winged stems. Blamey, Fitter & Fitter (When are A&C Black going to do a long overdue reprint???) describe the bracts as 'conspicuously swept back'. Smells good too.

Carduus crispus Welted thistle
Welted thistle on road, Folkestone Downs


Welted thistle is, I think, less distinctive. It has large flowers with woolly bracts and spiny stems. The stems are described as 'naked' just below the flowers, which you can see, just, in the photo.

Bedfordshire is nowhere near the sea. I don't think there are many records for slender thistle (Carduus tenuiflorus) in Bedfordshire. Priory Country Park was not the place I expected to find it on Tuesday. And to be honest, I would have walked past it had I not seen it so frequently in East Kent.
  
Slender thistle, Priory Country Park

There were a few plants growing right next to the park visitor centre on some rough ground. Perhaps they were imported on the wood chippings?

UPDATE 28/6/2011: Apparently the bark chippings at Priory CP were not imported from off-site. Some trees were cleared from the site so thistle seeds were probably in the seedbank. The site is a former gravel pit so topsoil would have been brought in for landscaping. John Dony (in his Flora of Bedfordshire, 1953) says slender thistle is a rare wool adventive.

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