The BBC link below has some useful information.
Potatoes don't spread out very far underground. The root where the potatoes grow, mostly goes straight down. You can plant lots of other vegetables nearby.
Potatoes are ready to harvest when the plant's foliage turns yellow and begins to die back. This usually occurs about 2-3 weeks after the plant flowers. You can also gently dig around the base of the plant to check the size of the potatoes - they should be mature and firm.
potatoes are a plant. they are considered a starchy food.
Potatoes have "eyes" that produce new potatoes. The person growing them cut the potato with the eye and plant them.
It is a common misconception that potatoes are roots. They are actually tubers, and thus potatoes are a part of the potato plant. They are not the roots of any plant.
Botanically, yes, they are a vegetative plant organ. Potatoes are the tuber (root) of a fruit bearing plant. But nutritionally potatoes are considered a starch/carbohydrate and not vegetables.
A potatoes plant stored starch
APRIL
no
corn or potatoes
Vegetables
When planting potatoes, it is recommended to plant them with the eyes facing up. This helps the potato sprout and grow properly.