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Oxalis tuberosa

Oxalis tuberosa

Connor continues to be responsible for assembling this series:

The second of three entries featuring plants from the GFU for Underutilized species exhibits Oxalis tuberosa of the Oxalidaceae. Thanks Hannes and Paul! Photo courtesy of the International Potato Centre (CIP).

Oca is a starchy edible tuber that was domesticated in the Andes in South America. It is at least as hardy as the potato and grown in a similar way but it is not as susceptible to pests and diseases as potatoes.

When freshly harvested, the tubers have a pleasant acidic flavour. They are consumed cooked or baked. They can also be eaten raw in small quantities. Exposed to sunlight for a few days, the tubers lose some of their acidity and become more pleasant to eat.

Oca can be prepared, like most tuberous vegetables, by being boiled, baked or fried. In the Andes, it can be part of stews and soups, served like potatoes or served as a sweet. Oca is eaten raw in Mexico with salt, lemon and hot pepper.

Oca forms tubers only at a daylength of under 13-14 hours. Outside of its native area, such as in higher latitudes, autumn frosts may kill the plant before the tubers are fully developed. Under such conditions, commercially relevant yields are hard to achieve.

Projects to improve poor rural families' quality of life through the management and commercialization of oca have been implemented in various places. One example is the village of Puno in southeastern Peru where infant mortality and illiteracy rate are almost twice the national average. Mismanagement of organic garbage and loss of biodiversity has created serious problems with environmental deterioration, and families have little access to employment and income.

The project aims to contribute to the improvement of environmental conditions and increase the incomes of rural families in the Lake Titicaca area by encouraging farmers to produce oca. The project is targeting a new beneficiary group, Puno's indigenous people, by training them on how to make marmalade from oca. The project will also produce 40 metric tons of organic fertilizer from manure and crop residue, manage roughly 10 hectares of oca, and establish six rural micro enterprises.

Some Producers/Retailers/Distributors


They are beautiful. I wonder if they are at all related to the regular potato as us Westerners know them. One time a lady gave me some Jerusalem artichokes that weren't too bad. She grew them instead of potatos, just for fun.
Good article... Thanks so much.

What a wonderful picture. I had no idea that they came in such a variety of shapes and colours. Does this affect their flavour at all? I've only ever seen or eaten the pink nobbly ones - which are delicious - but I would love it if someone in New Zealand started to market such a variety as you display.

Beautiful! And the only Oxalis I'm really familiar with are the Shamrocks (being born on St. Patrick's Day). But the corms look like miniature versions of the tubers shown above. I'd be interested in seeing the leafy portions of these.

I chew on wild oxalis stems occasionally (O. stricta) ... they are tart! So I found it interesting that there's a truly edible Oxalis product

These are so beautiful! I'm also only familiar with the 4-leaved oxalis which grows in our garden & woodland (London,UK), must admit I didn't even know they had small corms. I'll be reading up about that for the near future, it's truly whetted my appetite (in both senses!). Our garden oxalis always gets a rust fungus & dies so maybe never has a chance to develop a corm??
Thanks so much for the wonderful BPotD!

Here is a great book online that has a lot of information about many andean crops, including oca.


Oops, meant 3-leaved, of course!!

Gorgeous critters!
Do these tubers contain oxalic acid and how does that effect their nutritional value?

i also know of the flowering
plant oxalis my mother had
one on her window sill

perhaps there are markets
here in the states
i live in florida whole foods
might know of it

always interesting around here

I'd love to try to grow this here in BC - but I haven't found tubers for sale. Does anyone know where they are available? Heres a US co that sells to US only: http://www.horizonherbs.com/product.asp?specific=2081

Is the acid, Oxalic? If so be careful.

"I wonder if they are at all related to the regular potato as us Westerners know them" - no, they're not. Oca is in the family Oxalidaceae, Potato in the family Solanaceae.

"I'd love to try to grow this here in BC - but I haven't found tubers for sale" - you'd presumably run into the high latitude difficulties mentioned in the account above: "Outside of its native area, such as in higher latitudes, autumn frosts may kill the plant before the tubers are fully developed. Under such conditions, commercially relevant yields are hard to achieve".

Well this is amazing!! I love this plant. I also knew it as a shamrock plant. Just learned last year it's real name Oxalis. My daughter has a purple leaved and lavender flowered one that she has had for years in her home. I have had the green leaved white flower variety and the purple one but both died off last year. (I had them outside). I did notice the little corms in the pot. Awww isn't mother nature grand?

Here in New Zealand we call the pictured corms "yams". I know that true yams are different, but that's marketing for you. They're a lot bigger than the small corms on ornamental flowering oxalis, quite a few varieties of which are a pest weed in our gardens (north of the Waikato, anyway, thanks to our warm winters). Some varieties are very non-spreading, others (the pests) are prolific producers of tiny pup bulblets which break off and lurk in the soil when their parent is weeded out ... Mind you, when they flower at least they're pretty weeds!

I've grown them for several years. I purchased my base stock from Nichols Garden Nursery in Albany, Oregon.

Cooked, their taste is hard to distinguish from "baby" potatoes, but with a more delicate texture.

I think oxalic acid breaks down during cooking, as there was no detectable flavor in the cooked tubers; however, it is probably worth a little research before eating it raw (I haven't tried it that way myself).

I grow them within their native range - tuber colour is a matter of cultivar and doesn't seem to affect flavour any.

I've eaten them raw, but only after exposing them to sunlight for a couple of days. They are very tasty with salt. The oxalic acid content of the tubers is very low to begin with, and the sunlight seems to break this down. Certainly cooking does.

I wouldn't actually be too concerned with the oxalic acid content in Oca, since both Spinach and Rhubarb contain more.

Connor I do thank you for all the great photographs and the information to go along with it all. I enjoy the photography and I am learning more and more each day.
Please keep up the good work. You are appreciated for all you do in educating the public.
Thank you,

Thank you for featuring oca for your botany photo of the day! It is a beautiful photo, and oca is a beautiful crop. I have been researching oca for over 14 years, though, so I hope you don’t mind if I make a few friendly corrections/comments on the image and the other folks’ comments.

First, not all of the tubers in the image are actually oca. I’m sure that the International Potato Center didn’t tell you that all the tubers pictured are oca, because I know that they know their tuber crops. The ancient people of the Andean region domesticated tuber crops from four completely different plant families! That doesn’t even count the many other Andean crops that are technically roots or corms, only the tubers. These are the potato in the Solanaceae family, oca in Oxalidaceae, ulluco in the Basellaceae, and mashua (also called añu or isañu) in the Tropaeolaceae (that’s the same family as the garden nasturtium). I don’t think there are any potatoes in the featured picture, but there are tubers shown of all of the other three Andean tuber crops in the photo. Some of the pictures on Eric’s FLICKR site are ulluco as well, rather than oca. Regardless of whether some of them are not oca, they are all lovely!

Second, there are hundreds of different species of Oxalis, and only oca is cultivated for tubers, so neither the weedy ones (e.g., O. stricta), nor those ornamental ones sold as “shamrocks” will ever bear tubers like the ones in the photo. Many of the ornamental kinds have bulbs, but they are quite distantly related to the ones with tubers.

Check out the online book that Sunny linked to above, as well as the International Potato Center, for good information about oca and the other Andean tubers.

The sad thing is that oca is rapidly disappearing from some rural areas of the Andes, so I hope your feature will increase interest in the crop!

Eve - thanks for your input and ID info. I'd love any corrections you may have on my IDs. Feel free to email me - eric@erichunt.com

where can I purchase the following plants?

-tree collard
-bush kale
-salt bush
-air potatoe
-fragrant spring tree

thanks for this photo. I like Oca, Mashua and Ulluco and try to spread this plants. I am very interested in different colors.
It is alway difficult to get this tubers. Therefore I try to get an international platform for change.
Excused my bad english

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