SC - Hazel Leaves?

[Rose]

I'm looking at the recipe for "Noteye" from Harleian MS 279, and it calls 
for hazel leaves.  They're ground small in a mortar, and then the juice is 
wrung out and added to the meat and almond milk mixture.

So, are hazel leaves just the leaves from a hazel tree?  What do they taste 
like?  Does anybody know of a source for them?  Is there a reasonable 
substitute?

Thanks,
Rose