Ah, potatoes—one of the greatest vegetables ever. Boil ‘em, mash ‘em, stick ‘em in a stew—their deliciousness is matched only by their versatility.
They’re shaped rather round like fruits are and may not be the first vegetables you think of, but they are clearly vegetables nonetheless. They have eyes, not seeds, and are thus not even fruits botanically, which is a requirement for something to be a fruit culinarily. Instead they are tubers botanically, a special storage organ grown out of the stem underground.
To further evaluate their culinary properties: They are not sweet or juicy at all. They are super starchy. You eat them as part of your main meal, not dessert. They grow underground annually. They last quite a while if stored properly. You always cook them before eating them. These are not the qualities of fruits either. They’re vegetables through and through.