Hi, Paul,
I think your marrows are what we call "zucchini". For a picture, go to
Google and click on "Images" above the box. Then type in a word
(Marrows, for instance) in the box, and you will get pictures.
There are a number of references to zuchinni on RFC. For that, type
"Zucchini" in the Google search box.
Excuse me if I explain more than is necessary. Hope that helps.
Regards,
Nancree