What kind of gourd is this?

Question

My neighbor is growing this vegetable and forgot what kind of gourd it is. Is it a bottle gourd or a type of butternut squash?

And here's the flower:

Answer 1

I'm fairly sure that's a bottle gourd. In my experience butternut squash fruits start out quite ovate and then develop a swelling when they get larger (or don't). Also all the butternut flowers I've seen have been yellow and much more trumpet shaped, and a quick google of bottle gourd flowers shows them to look very much like your photograph.