Think of marrow as grown up Zucchini. Native to England, marrows are bland green, oval summer squash that can grow to the size of a watermelon. Zucchini and courgette are the same thing – zucchini Italian name and courgette French. Both mean baby marrow. You can also use eggplant for this dish.
Served as part of the fourth course in 1st class on the Titanic, this would have been an extravagance, since marrow is only available in summer, meaning the ones served would have been grown in green houses.