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 INTRODUCTION

Since the 1950's I had read in such manuals as the Vilmorin Catalogues, Le Potager d'un Curieux, Prof. D. Bois Encycopédie Biologique etc. much praises about the "Vitelotte". It was only in the 1980's that I discovered by accident a "new" variety called "Purple Congo" in Australia. I have now grown it, processed it, nursed it, observed it, eaten it in any imaginable way for 2 decades. Having come across some new scientific material about these kinds of potatoes I thought it was about time I return to pen and paper for the cause of the humble purple potato.
A few comments on the "Vitelotte', which may be a synonym of  'Purple Congo, may be relevant here.  "Vitelotte" is the only name listed in the official European Cultivated Potato Database  today. In the past I have read about a black, a red and a purple vitelotte. Today Serge Jodra mentions a few more that excite my interest : " la Vitelotte jaune imbriquée; la Vitelotte jaune de Pigry; la Vitelotte rouge longue de l'lndre ou de Paris; la Vitelotte longue d'Islande, etc." How good would it be to see photos of these ?

GENERAL DESCRIPTION

The French description : " les Vitelottes ou Cylindriques : tubercules violets; allongés, cylindriques, yeux très nombreux et très apparents, et profondément enchâssés".
Cylindrical, elongated shape with many deep eyes. Certainly the following photos match. So far so good.

'Purple Congo' - This shot displays a mature tuber flesh and skin, and some immature tubers (or  "seed potatoes")  suitable for propagation.

'Purple Congo' -  In this shot the "seed potatoes" have been replaced with tubers of a fully mature plant. The tubers are larger and perfectly edible but not suitable for replanting because symptoms of diseases are apparent on the skin and often the inside of those tubers will reveal signs of damage by insects' larvae. The flesh surrounding those "tunnels" exudes a very unpleasant smell and of course tastes awful.

In their descriptions the Seed Savers highlight the thin white layer of  flesh under the skin of  'All Blue'. They also indicate that  'Purple Peruvian' provide the deepest purple colour.
Some authors (for example Chef James connected with  Purcell Mountain Farms) have mentioned that the eyes of  'All Blue' are rather shallow and the above photo seems to display this as well as a distinctly blue skin, as opposed to the dark-purple / black skin of  'Vitelotte'. Who would be better placed than a chef  to notice how deep the eyes of a potato tuber are. This suggests that 'All Blue' is a rather improved cultivar as opposed to the rougher looking, closer to the wild relatives of the Andean region, 'Vitelotte'  (See our gallery).

Well just when I thought I had it all worked out comes out of the blue (no pun intended) some new info that throws my theory out. 'Purple Peruvian' sold by Milk Ranch Specialty Potatoes  is purple in and out but has a white flower. Hum! Back to the drawing board...or ... is it ? Flower colour ?  good question.

H. De Jong  and A. M. Murphy (Agriculture and Agri-Food Canada Potato Research Centre), in their article (both English and French versions make interesting reading)  "Congo: A Versatile Blue-Fleshed Heritage Potato Variety with Many Names" mention that (partly based on DNA) a group of purple skinned  has been identified  (the Congo Group) which includes Congo, British Columbia Blue, MacIntosh Black, Nova Scotia Blue, River John Blue and Sharon’s Blue. To these could be added All Blue, Blue Congo, Congo Blue, Purple Congo, and Himalayan Black. These have purple fleshed varieties. A subgroup within this Congo Group has white flesh  (Purple Chief and Ruby Pulsiver’s Bluenoser). A small appendix notes that Vitelotte cannot be incorporated into the Congo Group. I would suggest that Purple Congo looks too much like Vitelotte and therefore should not be included either into the Congo Group. Perhaps that Purple Peruvian also could be close to Vitelotte and outside the above group.
This brings us to a possibility that the Vitelotte violette is an improved cultivar of the Vitelotte Noire (aka Vitelotte aka Négresse) and is therefore closer to All Blue than to the primitive Vitelotte of the Vilmorin catalogues. I rather think however than Vitelotte is the lazy appellation for either Vitelotte violette or Vitelotte noire as indeed this potato can appear purple, dark-purple or black depending on circumstances and / or whether one refers to the flesh or the skin. These considerations are mostly relevant to taxonomists, botanists and growers. From the culinary perspective however most blue or purple fleshed potatoes will show off  their outstanding colour in similar fashion (see 2 photos below for the possible range). Based on experience in the field and in the kitchen rather than on DNA I am putting forward the possible following division. The middle column is basically the Congo Group of De Jong & Murphy minus 2 "black" cultivars and 'Purple Congo', the right hand column is also the subgroup mentioned by these two authors. A few more likely synonyms as well as other foreign names have been added in each of the 3 groups.

In order to dress a more accurate table, one would need far more information than anyone seems to have on hand (or is willing to divulge). For each cultivar photos of flower,  new shoot, tuber, flesh would be a start.  Then  further data such as origin, days from planting to maturity, average yield, resistance to diseases / pests, uses in the kitchen etc. would complete the emerging picture.

Culinary displays
All of these "purple potatoes" once cooked and broken in a particular way can display an inside resembling a beautiful blue-coloured gem (having handled some of those in my brief "geological" carrier I am always reminded of those stunning rocks).

'Purple Congo' on top, 'Sapphire' (an improved cultivar with shallow eyes) on bottom

'Dargo Goldfields' an old cultivar gone wild in the Australian bush displaying the same beauty than precious polished rocks when sliced, crystals when broken-up (not succeeded yet in capturing this on film). See larger photo for a better appreciation.

A small note for the benefit of French readers. 
En ce qui concerne la culture, une bonne terre fertile produira des tubercules énormes. Il est prudent de ne pas attendre la fin de la plante cependant si on veut la propager car les maladies sévissent durant les dernières semaines. Récolter avant maturité fournira des "patates" assez grosses et de bon goût. Cette varietée est très tardive. En climat temperé (sud est de l'Australie) je laisse mes 'Vitelottes' / 'Purple Congo' (les noms abondent et les synonyms ne sont pas enregistrés proprement) se propager elles mêmes dans certaines parcelles et j'en prélève selon la technique acceptée. Résultat je n'ai jamais eu besoin d'acheter un tubercule en 25 ans. A vous de tirer les conclusions. J'imagine que les organisations biologiques en France peuvent approvisionner en vitelotte. Victor Renaud et d'autres enthousiastes aussi seront ravis d'en procurer.

Value of purple-fleshed potatoes, today and yesterday

To the native people of the Andean regions potato with coloured flesh had a special place. In addition to their use as food, potatoes with pigmented flesh were a source of dye and used in religious ceremonies. Today in health-aware societies, in terms of nutrition, such potatoes should be regarded as highly as blueberries or purple carrots or watermelons especially the purple-fleshed potato due to its high level in anthocyanin pigments  which have "possible health benefits as dietary antioxidants" say the most prudent doctors.  "There is considerable anecdotal and epidemiological evidence that dietary anthocyanin pigments may have preventive and therapeutic roles in a number of human diseases" say others more adventurous.
Coming back to our starting point growers have observed through the decennies that the 'Vitelotte' and the 'Purple Congo' (perhaps the same cultivar) have a higher resistance to degeneration than most modern potato cultivars so even if it had no other value - which is not the case of course, it would be of some considerable potential to breeders. Can you spot the ancestors of the Purple Congo in this gallery from the Centro Internacional de la Papa - PERÚ ? One species looking like our beloved potato is Solanum ajanhuiri Juz. et Bukasov  and it bears white flowers... but this is a very superficial dig (both linked images are from the Botanical and Experimental Garden of  Radboud University, Nijmegen, The Netherlands).

Date created: 20 / 07 / 2000
Authorised by Prof. Snow Barlow
Last modified: 25 / 10 / 2006
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