Zucchini is a squash, as are cucumber and watermelon, though you never would have thought so. When they are pre-fruiting vines, they all look the same as butternut and acorn squashes. Except I've seen zucchini grow as a large bush with large flowers.You can feed those flowers too. Rose petals are also edible, but I doubt flowers of any kind have much nutrition.
Some people might not believe this. Check it out on Google.
The rule has to be: Don't feed anything you are not absolutely sure is edible.