I looked up the term "terminal leaf" and couldn't find it (I think this is because I don't have a specialized biology dictionary). However I found a discussion on a forum where this term was used.
Now to the subject. I would put it like this:
"Mature leaves were collected from the upper half of the birch crown annually (except the four terminal leaves)."
or like this:
"Mature leaves (except the four terminal ones)were collected from the upper half of the birch crown annually ."
or even like this (but about this last sentence I would consult an expert in biology terms first):
"Mature leaves (except the four terminals) were collected from the upper half of the birch crown annually ."
Mind that I am not a native speaker.)
And I am too struggling now with the use of the preposition "for" with "except" in this case (except or except for?) )))) Only native speakers can help.
Last edited by englishhobby; 08-Jan-2013 at 10:49.
If I were a native speaker of English, I would never shut up.)