Do they mean "plantain" the banana-like tropical fruit, or do they mean "plantain" the common weed.

And the leaves you found - were they from the edible fruit or the weedy plant?

What was the recipe for?

It was a recipe for a big bite balm. And I believe they mean the plant and not the fruit, as the book from which I got the recipe lists the weed and not the fruit.

If the recipe calls for dried Plantain leaves and you think it means Plantago species, then I don't see any reason why the stuff you have found would not do the job. But Plantago major, the one usually used in herbal concoctions, is a very common weed. You could probably find some quite easily nearby unless you live in a hot dry area.