Culinarily, you can define vegetables using the basic food groups. Grains and starches are a distinct group and not part of the vegetable food group, despite the fact that they come from plants. It is easy to see that not all food that is plant-based is, culinarily, a “vegetable” when you consider things like fruits and nuts, which people have no trouble distinguishing from vegetables.
And yes, many things we culinarily consider vegetables actually fall under the scientific definition of fruit, and some “fruits” do not fall under that definition.
I think the distinction you’re thinking of is when something is milled. Wheat is milled into flour. Rice is milled to remove the husks. Corn is milled into meal. At that point you’re not eating the plant, you’re eating a processed plant product. Of those three, corn is the only one that can really be eaten as-is, so perhaps the distinction of when it’s a grain or a vegetable is more about if it was dried and milled first.
But all of that seems unrelated to potatoes, which are roots. You can make bread out of potatoes, and I don’t think anyone would try to argue that potato bread somehow counts as a vegetable. But a potato on its own, minimally processed and eaten relatively whole, seems to fit the definition of a vegetable by most definitions, culinary or otherwise.
Culinarily, you can define vegetables using the basic food groups. Grains and starches are a distinct group and not part of the vegetable food group, despite the fact that they come from plants. It is easy to see that not all food that is plant-based is, culinarily, a “vegetable” when you consider things like fruits and nuts, which people have no trouble distinguishing from vegetables.
And yes, many things we culinarily consider vegetables actually fall under the scientific definition of fruit, and some “fruits” do not fall under that definition.
Starches are just something a vegetable has, though, not something they are. Like protein and fiber.
If you exclude anything with starch from being vegetables, you’re also excluding beans, squash, lentils, carrots, peas, parsnips, corn, etc.
Corn is not a vegetable, it is grain. Is rice a vegetable? No.
I think the distinction you’re thinking of is when something is milled. Wheat is milled into flour. Rice is milled to remove the husks. Corn is milled into meal. At that point you’re not eating the plant, you’re eating a processed plant product. Of those three, corn is the only one that can really be eaten as-is, so perhaps the distinction of when it’s a grain or a vegetable is more about if it was dried and milled first.
But all of that seems unrelated to potatoes, which are roots. You can make bread out of potatoes, and I don’t think anyone would try to argue that potato bread somehow counts as a vegetable. But a potato on its own, minimally processed and eaten relatively whole, seems to fit the definition of a vegetable by most definitions, culinary or otherwise.