Unlike the orange cauliflower which carries a mutation, Purple Potatoes are actually a heirloom variety of potatoes. They are available year-round in some of the upscale grocery stores across the country.
Most common people think they're colored artificially, kind of like those odd-colored daisies you can buy in Walmart. Purple potatoes are rich in the anthocyanin, an antioxidant found in other blue, red and purple fruits such as blueberries and pomegranates.
Anthocyanins are powerful immune system boosters and have been shown to have some protective properties against various cancers. The odd looking (in my humble opinion) purple potatoes have deep violet, ink-colored skin and flesh. Some varieties, like the ones I bought are marble throughout the flesh. The purple potato is native to the Lake Titicaca region of Peru. Some of the cultivars are as many as 8000 years old.