Black Spud Confusion —

Back in 2010 I posted here about the black potato "Négresse" which I grow every year. The article kicked off some speculation about naming confusion between Négresse, the very similar Congo, and a third potato, Vitelotte...

Well grown examples (if I do say so myself) of the blue-black fleshed potatoes Congo(left) and Négresse.

Having grown Congo and Négresse together for a couple of years now, I can confidently say that they are not the same variety. Appearance, eating qualities, and resistance to tuber blight are similar, but...

—Négresse has a squarer shape than Congo (most obvious on fully mature tubers).
—Négresse tuberises slightly earlier (or at least gives more crop by early July when mine were killed by blight last year).
—Their foliage is noticeably different.
—Négresse has a shorter dormancy period.

I have said previously that I suspected Negresse was truly day-length sensitive (like oca); the plants will continue to grow without naturally dying back, until the first frost. Actually I now realise that very small tubers are formed by mid summer, so the plant is not day length sensitive. But they do need a very long growing season to reach the size of those in the top photo.

Here are my lazy beds in June last year, complete with authentic blight blackened foliage...

I was expecting to find no tubers at this time of year, but I was pleasantly surprised to find small tubers had already formed.

And then there is Vitelotte. Wikipedia says this is synonymous with Négresse. So do seed merchants Thompson and Morgan who are selling them as micropropagated mini tubers this year. Others say they are clearly different, so who knows. I certainly get larger tubers than those shown on the T & M site.

Changing the subject, an annoying problem with all these black potatoes is finding the well camouflaged tubers in the soil at harvest time. Missed tubers result in persistent volunteers which can be real pests amongst a following crop. No such problem with this new (as yet unnamed) variety...

...which has spectacularly prominent fluorescent pink skin and flesh!

Sunglasses not included.

What's that Other Andean Tuber...

...a bit like Oca, only dull brown, mundane, and suffers from lots of diseases. What's it called ... oh yeah -  the potato.

Straight away, I had better apologise to spud fans for that admittedly gross generalisation, and I do have to acknowledge a certain appreciation for Solanum tuberosum ordinaire when it arrives on my plate, even when it is dull brown, and agrochemical dependant.
But if we look beyond the few varieties grown en-mass for the supermarkets, it is actually a hugely interesting, diverse, and delicious food plant. For example...

Harvested 7th October

...these are the last of my spuds to be lifted - the late maincrop black-skinned and purple-fleshed Négresse. I've maintained this variety for a few years now, but there's very little information available about it. Some sources say it is the same as Vitelotte, and was brought from Peru to France in 1815. Cats tripe has photos of Vitelotte here and I'm not convinced they are the same. Vitelotte is said to flower rarely, which is not my experience with Negresse. Vitelotte shows white marbling through the purple flesh in all photos I have seen, whereas my Negresse is purple throughout, thus:

A US potato list gives it a mention here and surprisingly suggests that it is not Solanum tuberosum, but Solanum ajanhuiri.
So in summary, it's exotic, mysterious, beautiful and day-length sensitive (another way of saying 'late maincrop'!), all of which would be a fair description of Oca.

Thanks to Paul Coleman, potato breeder, for letting me try the next three varieties. All have something in common; they are crosses between Solanum tuberosum, and Solanum phureja.
The first, Mayan Gold (left below)...

... is commercially available and well enough known as a gourmet potato.
The second, nicknamed "Mr Nutty"  (centre) is more interesting, and cannot hide its tuberosum parent, Pink Fir Apple. It tastes fantastic! Here's another shot showing its graduated skin colour and primative good looks.





And finally a bright yellow-fleshed main crop which makes great buttery mash.
I've had universal unprompted positive feedback on the taste of all three varieties, so I'll be saving for next season.

Mayan Gold, harvested 22nd August.

And what's this all got to do with Oca? Not too much, except it's worth asking why the potato is a world nutritional mainstay, while Oca is almost unknown, when both started out alongside each other, with similar characteristics and limitations. Why did the potato benefit from selection and breeding in Europe, while Oca plodded along in Andean fields and terraces? It seems unlikely that the Conquistadors only picked up the plain-looking potatoes from markets when they were right next to spectacularly colourful Oca tubers. Maybe the tubers that looked best, and needed no cooking got scoffed by the ship's crew on the way home to Spain, leaving only the potatoes. That's my theory.

Anyway, Oca has some catching up to do.