Vitelotte is an ancient (quite like an heirloom rose) cultivar

Cultivar

A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...

 of blue-violet potato

Potato

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

.

Description

Vitelotte potatoes have a dark, almost black skin and dark violet-blue flesh thanks to a high content of the natural pigment anthocyanin

Anthocyanin

Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH...

. They retain their colour when cooked. The plants mature late and compared to modern varieties produce a fairly low yield. The tubers have a thick skin and thus store well.

History

Originally from Peru

Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

 and Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

, the Vitelotte variety is still commonly grown there.
It is supposed that they are a 200 year old mix of ancient types of Peruvian potatoes.