Fleurbird - Tuvok was really asking you to tell us what the theme is, so that people that do not have the quiz may be able to help you.
We are none the wiser
We now that it can be any of a series of veg in the cabbage family including all the wild cabbages - but as we do not know the theme, we cannot get any further than that
One of the themes was a European connection in this quiz - Does Brussells Sprouts fit.
Sorry the St Mary's quiz doesn't have an overall theme. It is divided into sections with headings. This clue comes under "Up in the Air" so for me Cabbage is hard to connect to that but thanks anyway.
Thanks everyone. I've got answers to all the rest and they are ok for the theme but I'm still puzzling over this one as I have for months! Hopefully the penny will drop in time!