Sonchus oleraceus: undomesticated but perfect for human consumption?

For the last 30 years, Sonchus oleraceus (https://en.wikipedia.org/wiki/Sonchus_oleraceus) has been an important - and perhaps the healthiest - part of my diet.

This herbaceous member of the daisy family is a common weed (https://www.researchgate.net/publication/334503437_Biology_impact_and_management_of_common_sowthistle_Sonchus_oleraceus_L) near my home, which has a mediterranean-type climate. The only way I have eaten it is pre-hominid, simply plucking the green leaves (https://en.wikipedia.org/wiki/Sonchus_oleraceus#/media/File:Leaf_of_Sonchus_oleraceus.png) and chewing them raw on the spot. I do not accept the flowers, even in the form of the buds.

I usually eat about 50 leaves at a time, on average several times per week during the cool and rainy half of the year. That totals about 5,000 leaves per year, with a break in the summer and autumn when S. oleraceus is largely unavailable.

I value salad in my diet, but I have found S. oleraceus so reliable and satisfactory that I have not bought any leafy greens from any sort of shop for the last 15 years. I simply browse when I am out and about, finding my favourite weed easily near sidewalks and in neglected gardens and vacant lots in this metropolitan area.

Herbicides are frequently used to kill weeds here, but it has been easy to find unsprayed plants, and in all these years I have never had the slightest negative reaction from my herbivory.

The leaves are less fibrous than those of dandelion (Taraxacum officinale, https://en.wikipedia.org/wiki/Taraxacum_officinale, which is scarcer here because of its preference for slightly neglected but frequently watered lawns). However, they are similarly bitterish and moderately astringent. I eat S. oleraceus not for its taste but for its salubrious effects.

It is perhaps ironic that I have never felt drawn to browsing Lactuca serriola (https://www.inaturalist.org/observations/66814011 and https://en.wikipedia.org/wiki/Lactuca_serriola), which is also common and weedy hereabouts. Lactuca serriola is, after all, the ancestor of the domestic lettuce (Lactuca sativa, see https://link.springer.com/article/10.1023/A:1008611200727).

The genera Sonchus and Lactuca both have a tendency for the leaves to be somewhat prickly. Sonchus oleraceus can be thought of as a 'relaxed thistle', in which the potentiality for prickliness is seldom realised and the leaves are therefore palatable. Lactuca serriola has a row of prickles on the abaxial side of the mid-rib of the leaf (https://upload.wikimedia.org/wikipedia/commons/9/91/Kompassla_08-07-2006_9.39.08.JPG), which are not thistle-like but are the more discouraging of the two. The prickles, though small, are obvious because the leaves tend to be held by the plant at right angles to the normal orientation. To me, L. serriola looks less appetising than S. oleraceus.

Lettuce has been improved by selective breeding, perhaps to a fault. The cultivated leaves are soft, succulent, virtually free of bitterness, and completely free of astringency. But they also seem hardly worth eating from a nutritional viewpoint.

Sonchus has hardly been subjected to selective breeding (https://jasonpadvorac.com/projects/sonchus-breeding/ and https://www.researchgate.net/publication/225167218_Crop_domestication_in_the_Compositae_A_family-wide_trait_assessment), but it presents, in its weedy natural form, something approaching the perfect leafy green from the viewpoint of human health.

At times over the past decades I have grown chicory leaves (https://en.wikipedia.org/wiki/Chicory) in my garden, as a closely-related but somewhat selectively bred alternative to S. oleraceus. I have also taken trouble to establish another weedy daisy more associated with the tropics, namely Bidens pilosa (https://en.wikipedia.org/wiki/Bidens_pilosa and https://www.jstor.org/stable/4252362 and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7099298/), as an annual volunteer in my garden. However, both attempts failed: in the case of Cichorium because the plants require too much care and in the case of B. pilosa because the shoots turn out to be too rich in kidney-irritating oxalates (of which S. oleraceus seems blissfully free).

Sonchus oleraceus remains so underappreciated in human diets that, in my decades of gratefully consuming it and recommending it to others in health-conscious circles, I have never seen it eaten by even one other person.

However, in my personal experience: my everyday environment has presented me with a choice of two species of weedy daisies - one a nominal thistle and the other the prototype for lettuce - originally indigenous to the same parts of Eurasia and gone cosmopolitan in the modern world. And the one that has stood the test of time, prevailing in my diet, is the one that has not been domesticated but could hardly have been improved even if it had.

Posted by milewski milewski, November 02, 2021 08:55

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Today I tried, for the first time, Lactuca serriola. The leaves taste similar to those of Sonchus oleraceus and as it turns out the prickles are not rigid enough to hurt my mouth. So next season I plan to eat both species.

Posted by milewski 7 months ago (Flag)

Thanks so much for this. Im also growing wild plants in my garden in Serowe Botswana that could be grown in high temps without too much water and be made into spinach. My background is chemistry so im interested in the chemicals in the plants that may be toxic or cause bitterness, that could be destroyed by boiling. My rabbit has a very selective nose and seems to be able to refuse to even taste many plants, He seems to be able to smell toxic chemicals. My principal is that if my rabbit loves it , it might be a spinach candidate. People here are willing to consume anything prescribed by a traditional doctor however bitter or potentially poisonous it may be but are very unwilling to try out new leafy wild vegetable ! My in-laws were herbalists and traditional doctors and sangomas but tended to die young compared with other family members who wouldnt touch a traditional medicine in Botswana. Have you tried Sesuvium sesuvioides which i think has been collected as a component of spinach in northern Namibia. What about Chenopodium species ? Im trying to cultivate chenopodium album which seems to be quite tolerant blazing hot October sun here in Botswana.

Posted by botswanabugs 6 months ago (Flag)

@botswanabugs Many thanks for your engaging report on your experiences in Botswana. I have not tried Sesuvium, but I have a bit of experience with Chenopodium, which I suspect to be rather rich in oxalates in keeping with the general trend in the Amaranthaceae. Chenopodium is interesting in that some species have succulent, bright-hued fruits and seeds dispersed and sown by birds. I have tried a local species, Chenopodium baccatum (https://www.olelantanaseeds.com.au/product/rhagodia-baccata-berry-saltbush-seeds-x-20/ and https://www.cottesloecoastcare.org/rhagodia-baccata/), and I was so surprised at the unpleasant taste (with a particularly persistent aftertaste) of the ripe, edible-looking fruits that I would dismiss this species as too unpalatable ever to eat again. I avoid even commercially grown 'spinaches' because of the problem of oxalates. Here in Australasia a species of Aizoaceae called 'warrigal greens' (https://en.wikipedia.org/wiki/Tetragonia_tetragonioides) is celebrated somewhat as 'bush tucker', and it has grown as a weed in my garden, but again it is far inferior to the innocuous daisy weeds such as Sonchus, Lactuca and Taraxacum. Since writing this Post I've been eating Lactuca serriola, and it tends to be pricklier, more bitter and more latexy than Sonchus oleraceus, but even L. serriola is, in my opinion, superior to any amaranth for raw leafy greens. I've grown Portulacaria afra in my garden here in Australia and its shoots are edible, with a sourish taste, but again I'm not drawn to much more than the occasional nibble. Your mention of your pet reminded me that the domestic rabbit reputedly likes to eat the leaves of Erythrina, suggesting some possibility that these leaves might also be edible for humans. Erythrina is a common street tree here but I have not tried them.

Posted by milewski 6 months ago (Flag)

Thanks @milewski I think I need to get more rabbits as food testers. Im sure they all have their own tatse preferences just as we do and i need more in case a few die by eating poisonous plants. I shall certain test out some cultivated erythrina leaves on Ryan the rabbit. Im sure Ryan doesnt have a full and perfect knowledge of plant toxicology or a fear of kidney stone pain ! I wonder if eating calcium carbonate limestone ( as an alternative to milk based products like youghurt/cheese) to precipitate the oxalic acid as an insoluble oxalate in the gut would help. I realise in southern/central Africa socium bicarbonate is added to a lot of leaf greens in preparation but this wouldnt precipitate oxalic acid. I think it just make the greens greener !

i understand that portulacaria afra- which is rich in tasty tangy oxalic acid is important in diet of south African elephants in some places. Do they get kidney stones ? Just wonder if any wild animls get painful kidney stones. Is it true that the p. afra is part of Cape Town salad dishes ! Perhaps cheese in the salad helps. Your articles are so interesting and they will give me weeks of reading and digesting, regurgitation and then rereading. there 's a lot to chew over.

Im interested in a shrub here in Serowe central botswana called pouzolzia mixta. I find plenty of small trees amongst the remains of fortification walls on tops of hills. The plants only seems to be able to grow well between the rocks on top of hills. One hill fort in my neighbourhood has about 25 trees growing in its basalt wall remains and i find two plants in the wall of another hill fort about 5km away.
Either the pile of rocks provide the most ideal habitat for the trees or the trees were once planted there by the occupants of the hill forts. Ive found that pouzolzia mixta is not eaten as a spinach in Botswana but is used for treating runny guts. here. Last time i visited the hill fort I found two traditional docs with an adze removing a large piece of pouzolzia mixta root. They said they need it for healing gut problems after a person has had an operation on the guts with stitches. Though the plant is not eaten here in Botswana as a spinach Ive found it is used in spinach making in northern Namibia. I just wonder if the bushes of pouzolzia mixta were cultivated on hill forts 139 years or more ago or did the thrive there naturally !

Posted by botswanabugs 6 months ago (Flag)

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