I tried to use YULE (as in Yule Log?).... but that didn't work.....
Bib's sentences, up above, have clues in them. I was thinking that if 'dry' was a clue, that would work for RYE (not only do they rhyme, but a 'rye' sense of humor is a 'dry' sense of humor?)
I think 'milked' was a clue, and I think 'drip-fed' was a clue. 'Milked' might be a clue for 'cowslip', but that's more than 4 letters. Or, maybe it's a clue for the language???
Oh Dear, I can't find any more plants that begin with the letter Y.