Luther Burbank is the father of the Idaho potato, the Burbank Russet potato, to be precise. This is the tater that comes to mind when you think of this noble tuber. Burbank only had an elementary school education but he was passionate about science and is credited with an incredible assortment of contributions to horticulture. (He also developed the Shasta Daisy).
Burbank Russets are easily identified by their smooth brown jackets and creamy white flesh. They're excellent mashed, baked, fried, creamed, riced, diced.... You get the picture. As a vegetable, it's difficult to come up with anything quite as versatile.
Today the potato has taken on a rainbow assortment of hues. Yukon golds have rich, yellow flesh, and you can even find purple taters that have an interesting tint. Somehow, purple mashed potatoes don't seem all that appetizing, but there's no accounting for personal preference.
Pontiac reds have a deep red skin and white flesh and are preferred by many for their sweet, smooth consistency. They're often served with the skins on.
That brings us to one color that's not on the menu. Green. Just like its nightshade relative, the tomato plant, the potato has leaves high in alkaloid toxin. These can cause illness if ingested.
The potato tuber is the edible part of this plant. Potatoes exposed to sunlight will develop green patches on their skin, and sometimes this greening extends into the fleshy part of the tater. This green is chlorophyll and indicates that solanine is present. This has a bitter taste and is not good to eat.
If the green patch is small, simply lop it off and you can safely use the rest of the potato. However, if the green has turned the interior of the potato an off-white, greenish hue, discard the potato. It's not going to taste good or be good for you.
White, yellow, red, purple = Yes! Green = No!