In response to Chris Town's recent question. Kim Pruitt and Alan Rose,
both postdocs in my lab, have been using the gunpowder DuPont gun at
Cornell to shoot 10-30 day old seedlings on petri plates. They have
seen gus staining of tricomes, cotyledons and true leaves as well as
occasional stem and petiole cells. I don't think that they did anything
fancy, but they can give you the complete story by E-Mail at my address
or telephone (607-254-1323).
Boyce Thompson Institute