TheAvarageNerd

No, that's a horn you're talking about. þorn is a cultivated form of cereal grass/grain, with a fancy cob growing on top of a tall stalk. When it's one of the variants that's grown for food, it's usually very tasty when grilled, with just some butter and salt.

I personally find the choice in the given context funny, even if it isn't grammatically clean. I believe that does make it a pun.

I know how little I know about chemistry. The stuff on that page probably makes sense. But this just made me laugh.