There is not just one but a whole botanical storehouse of sorrels in the world and several of them are useful perennial vegetables.
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| Many 'sorrels' in many places |
Sorrel derives from an Old French word surele which has its origins in sur of Germanic origin meaning 'sour'. The sour, lemony flavour of sorrels is attributed to oxalic acid in their leaves (found in many other vegetables including spinach, chard, beets, carrots, leeks, rhubarb and quinoa). But it seems to be more complicated than a simple more oxalic acid equals more sourness relationship. If the sourness in sorrel is caused by oxalic acid why does spinach taste less sour when it has higher levels of oxalic acid? See my note below*.
All the sorrels I know about so far are in the Rumex, Oxyria or Oxalis genera (not counting roselle (Hibiscus sabdariffa) which is sometimes called the sorrel plant after the popular Carribean drink which is made from its red calyces).
Here's a run down of some sorrels for the perennial potager:
My personal favourite is garden sorrel (Rumex acetosa), a robust, prolific grower with good-sized leaves which have a refreshing acid taste. (It is one of about two hundred species in the Rumex genus - most are known as 'docks' but the particularly sharp flavoured ones are usually known as 'sorrels'). There are several cultivated varieties of Rumex acetosa including some non-flowering forms which crop well all year.
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| Rumex acetosa - garden sorrel |
In previous posts I've used this sorrel in sorrel soup, goat's cheese and sorrel tart and sorrel and potato gratin.
Rumex acetosa is sometimes called French sorrel but so is Rumex scutatus, buckler-leaved sorrel (or 'true French sorrel'!)
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| Rumex scutatus - buckler-leaved sorrel |
To me Rumex scutatus has just the same delightful flavour as garden sorrel but is far more of a fiddle to pick - but I've heard it said that chefs regard it as having a superior texture and flavour. It is a lower-growing (to about 30cm), more spreading plant which self-seeds very easily and could be very useful as a ground-cover.
Red-veined sorrel (or bloody dock) Rumex sanguineus is a beautiful plant especially in spring when sunlight shines through its young leaves and illuminates their delicate red-veining.
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| Rumex sanguineus - red-veined sorrel |
Very young leaves are pretty in a salad but in my experience (gardening on a neutral clay soil) it is not long before the leaves become coarser and lose their sharp fresh flavour.
(Rumex acetosella is also worth a mention as, like Rumex acetosa, it is another common native of the British Isles. It is known as sheep's sorrel and more popular with foragers than gardeners. It is not one that I grow; I don't know of any garden cultivars and there is a danger that it might create a weed problem as it spreads quite vigorously by runners. But perhaps it could be useful for a difficult patch where little else will grow as I've read that it can cope with dry, acid soil.)
A couple of docks which are also often listed amongst the sorrels are patience dock (Rumex patientia) which grows particularly tall and monk's rhubarb (Rumex alpina). My patience dock isn't big enough to harvest yet and I don't have alpine dock but they are both traditional pot-herbs and said to be worth cultivating as perennial vegetables.
Just two species make up the Oxyria genus: Oxyria digyna (mountain sorrel) and Oxyria sinensis. Mountain sorrel is very hardy, growing as it does in the Arctic and on mountains in the northern hemisphere. Mine grows happily in the shade of the backyard and its thin lemony leaves are very useful for adding to salads.
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| Oxyria digyna - mountain sorrel |
But it seems to be quite a variable plant as many photos of it growing in rocky mountainous spots show thicker succulent leaves. Oxyria sinensis looks a bit like it but has handsome frilly leaves. I haven't heard of it being used as a food plant but that might be because it would be difficult to harvest - I think it grows mostly on steep slopes in the Himalayas in China.
There are about eight hundred Oxalis species. Many have 'sorrel' or 'wood-sorrel' as part of their common name. They occur in most regions of the globe but particularly in the tropics.
I have tried to introduce Oxalis acetosella, common wood-sorrel (native to Britain), into our backyard as it will grow in shade but I think it has perished. Here is Oxalis acetosella growing near Darmstadt in Germany.
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Common wood-sorrel [Rudolf Schäfer  ] |
I will try again - it is a very fiddly plant to pick but quite adorably dainty with white or pink flowers usually etched with lilac veins.
I don't know much about the other wood-sorrels but Oxalis oregana, redwood sorrel, is recommended by Martin Crawford in 'How to grow Perennial Vegetables'. It is another pretty one:
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| Redwood sorrel [Miguel Vieira ] |
It's also worth saying that the leaves of oca, Oxalis tuberosa, usually grown for its tubers, have that same sorrel flavour. (I believe oca was named South American wood-sorrel by European plant hunters when they first encountered it). Always good to know when you can get two crops from one plant!
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| Oca foliage |
Finally (and really just for fun) I wondered if this next one might be popular eating when I first heard its common name:
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| Candy cane sorrel [peganum ] |
It is called candy cane sorrel! - or Oxalis versicolor. Those leaves are pretty tiny though and I haven't read of anyone eating it - more of a feast for the eyes than the stomach perhaps.
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*[I set off up a sidetrack whilst writing this post in order to find answers to several questions about oxalic acid and diet. But I found myself in a maze of contradictory statements and evidence. I now have just more unanswered questions! These are some of them:
Is it a well-founded fact that oxalic acid in vegetables binds with their calcium, magnesium and iron content making these minerals nutritionally useless? Or is there so much more mineral content in oxalate rich vegetables like spinach in the first place than in the average vegetable that there will still be plenty left to be absorbed?
How can oxalic acid be the cause of the reported fatal toxicity of rhubarb leaves when the levels in spinach are almost as high? If oxalic acid isn't the sole or main cause of the toxicity what is? Do the post-mortems of people believed to have died from rhubarb leaf poisoning really support that conclusion?
How good is the evidence that oxalate-rich foods increase the risk of developing calcium oxalate kidney stones at all? Is there good evidence that oxalic acid plays a role in preventing illness?
There is at least a general consensus that you have to eat an excessive amount of oxalate-rich leaves to cause health problems. I just eat and enjoy without worrying. So my appetite is satisfied - but my curiosity isn't!]
N.B. I sell a range of perennial vegetable plants on my website.