Foulroyce

 
Occasionally I seek help with a word on this blog. Foulroyce is just such a word.

I came across it in the letters of John Clare (Feb 7th 1825:- "I always admire the kindling freshness that the bark of the different sorts of trees & underwood assume in the forest – the foulroyce twigs kindle into a vivid colour at their tops as red as woodpigeons claws..."

I assume foulroyce was a dialect name for a particular plant. The study of such names was at one time of great interest to me but I never came across the name foulroyce. Has anyone any idea which plant it might be? (Or, if my assumption is incorrect, an idea what the word might mean?)