I'm sure you all have it on your allotments....but it is a creeping weed with strawberry like leaves, long black tap roots.  Not buttercup.  Any ideas?
			
			
			
				    I know the one you mean, called cinquefoil I think. The roots can be very hard to completely remove.
			
			
			
				Have a look on this website which shows both weed flowers and leaves
http://www.dgsgardening.btinternet.co.uk/weeds.htm
			
			
			
				Thanks JJT, I think you cracked it!