Does it have to be vegetative cells? If you can get hold of
gladiolas, the pollen is certainly naked-eye visible, and the ovules
from a cross-section of an unpolinated/unopened bud's ovary will be
single cells, right?
Then there's a coconut. Technically, all the milk and solid white in
a coconut is one huge, multinucleate cell. (It's endosperm, but there
are no walls). Interesting, but perhaps not useful for your demo.
Might also conisder the moniliform hairs of Tradescantia filaments or
Gaillardia flowers. If the hairs aren't single celled, then each
"bead" on the "string" will be, and they're pretty visible.
Moinque Reed
