The artichoke, a crop to rediscover

There are many species of thistle, mainly found in countries bordering the Mediterranean. From wild ones, which we can admire during the summer months along the roadside edges and fallow fields, to those cultivated for consumption. They all share spiny stems, needle-like pointed leaves, and beautiful flowers in pink-violet colors.

It is not loved everywhere. In fact, it is often considered invasive and a 'weed.' In North America, milk thistle is regarded as an alien species and farmers must weed it out every year. In most French regions, on the other hand, there is an actual law requiring farmers to remove all wild thistles from the land by mid-July, under penalty of fines. (1)

But, approaching cautiously to avoid the thorns, the plant reveals its fascinating geometry.

Every part of the thistle can be consumed, from root to flowers, and it boasts numerous beneficial properties.

Thistles, between history and legend

The cardoons were already known by the Egyptians as demonstrated by their fossilized findings inside the tombs of some pharaohs. Pliny the Elder describes it in his 'Naturalis Historia' among the spiny plants and recommends it for eliminating excess bile. (2)

Scotland has chosen the thistle as a national symbol and linked it to the Latin motto Nemo me impune lacessit (Whoever provokes me will not go unpunished). The legend says, in fact, that a group of Vikings wanted to surprise the Scottish warriors in their sleep. One of the invaders, however, stepped on a wild thistle and his cries of pain woke the Scottish warriors who foiled the country's capture. (3)

Another legend It is said that Mary, seeking a safe refuge to hide Jesus from Herod's will, placed him under the leaves of a large thistle. Herod's guards, when they passed by, frightened by the large thistle spines, passed on. Mary was then able to relax and breastfeed Jesus. To thank the plant for the protection offered, she let a drop of milk fall on the green leaves. Since then, the thistle leaves have been adorned with bright white streaks. The plant was later renamed Milk Thistle. (4)

The spiny charm of thistles

The thistle (Cynara cardunculus) is a herbaceous plant that belongs to the Asteraceae family. It includes three botanical taxa,

• the wild perennial thistle (C. cardunculus L. var. Sylvestris (Lamk) Fiori),
• the cultivated thistle (C. cardunculus L. var. Altilis DC.) and
• the artichoke (C. cardunculus L. var. scolymus L. Fiori).

There are multiple varieties, especially wild ones. (5) They are generally perennial plants with a biennial growth cycle, meaning that in the first year they produce a basal rosette and only in the second year the plant blooms completely.

Most species It has an erect and winged stem with thorns, but no leaves. When present, the leaves are generally found at the base of the plant and are also edged with thorns. The flower buds, made up of many small flowers, have a perfect geometry and colors ranging from blue, magenta to violet. The flower rests on thick and pointed bracts that seem to want to protect the seeds contained inside. Indeed, in winter, the seeds of the thistle represent a valuable food for birds, but only a few manage to overcomethe barrier of thorns. One of these is the goldfinch. (6)

Properties and uses of the thistle

The thistle It has been known for its properties since ancient times. It was consumed as a treatment for liver disorders and to aid digestion. It consists of 94% water, has a low caloric content, and every part of the plant contains important nutrients. For example, the roots are rich in inulin, used as a prebiotic in cases of diabetes and hypercholesterolemia.

The plant parts of the thistle contain saturated fatty acids (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA), particularly palmitic, oleic, linoleic and gamma-linolenic acids. The plant is low in fat and the highest concentration of lipids is found in the seeds. It contains various minerals – potassium, sodium, calcium, magnesium, manganese, iron and zinc – and vitamins such as vitamin C and B-group vitamins. (7)

The effects of the thistle on metabolic disorders

Researchers have demonstrated that the thistle, together with the artichoke, has a hepatoprotective function, normalizing enzyme levels in liver cells. Additionally, in a study where it was administered alongside bergamot, its ability to counteract the onset and progression of hepatic steatosis was observed. (8) It also helps to reduce blood lipid levels, thus performing a lipid-lowering activity, and to prevent the onset of cardiovascular diseases. (7)

The industrial use of the thistle

The plant of the thistle is also suitable for many industrial uses. The flower, for example, is used as a vegetable coagulant for the production of certain DOP cheeses and could represent a valid alternative to animal rennet. The large amount of cellulose makes the thistle applicable in pulp production. Finally, its content of hydroxycinnamic acids and sesquiterpene lactones makes it applicable in the energy sector, for the production of biodiesel and biofuels. (9)

Varieties of thistles

Milk thistle

Milk thistle (Silybum marianum) is, as we have seen, a fascinating species of wild thistle. Although its use in cooking is not widespread, the leaves, flowers, and seeds are rich in nutritive and bioactive compounds used in herbal medicine. In particular, the seeds possess antioxidant, hepatoprotective, antifibrotic, anti-inflammatory, stabilizing, immunomodulatory, and antitumor actions.

The seeds Milk thistle seeds contain 42% fiber, 20% proteins and are rich in most essential amino acids, especially leucine, valine and lysine. The oil obtained from the seeds is rich in linoleic and oleic acid that can make it a valuable food. (10)

The ‘hunchback’ thistle

The thistle most famous for food use is the hunchback thistle of Nizza Monferrato (Cynara cardunculus L. var. altilis D.C.). Its cultivation is particular and tiring, so much that SlowFood has recognized and protected it with a presidium. (11) It is sown in May to be harvested in October. In September, when the plant is already developed, it is bent and covered with soil. In this phase, the thistle stems swell and lose every trace of chlorophyll becoming white. And they bend under the weight of the soil becoming, indeed, ‘hunchbacks’.

After one month the thistles are ready and very tender. In fact, they can be eaten raw, being sweet and crunchy. It is the main ingredient of Piedmontese bagna cauda, a sauce based on garlic, extra virgin olive oil and anchovies.

The Chieri thistle

Also in Piedmont another variety of edible white thistle is cultivated, the ivory white thistle of Andezeno or Chieri thistle (Cynara cardunculus). The leaves are narrow and jagged, spiny and tender. The cultivation cycle is similar to the hunchback thistle, but the blanching technique changes. Once, blanching was done by earthing up to two-thirds of the plant. Today, it is obtained by surrounding the plant with straw, paper, or black plastic sheets.

After the harvest, the ribs are freed from filaments and boiled in acidic water with lemon to prevent blackening. The thistle can be eaten both raw and cooked and is also excellent paired with eggs and cheese. The ivory white thistle of Andezeno is protected as a Traditional agri-food product of Piedmont. (12)

Other types of edible thistle

There are other varieties of thistles produced for consumption, such as Bologna thistle, Tours thistle, Giant Romagna thistle, and Ivory thistle of Isola d’Asti.

The taste The taste of cardoon is similar to that of artichoke, but more delicate and bitter, reminiscent of celery. Before cooking them, it is advisable to soak the cardoons in water and lemon to prevent them from darkening. After boiling, they can be sautéed in a pan with oil, breadcrumbs, and garlic. They are also excellent baked au gratin or breaded and fried.

Conclusions

The cardoons are a rustic plant, capable of growing even in the driest areas without requiring water, not even in the summer months. Its cultivation does not even require fertilization operations. Given its beneficial effects on human health and various industrial uses, it is a plant that deserves to be rediscovered. Having been recognized as a competitive energy crop, it could represent an opportunity for economic recovery and development of rural areas in the Mediterranean region.

Alessandra Mei

Notes

(1) State services in Indre. Field thistle: mandatory control https://www.indre.gouv.fr/Actions-de-l-Etat/Agriculture-Developpement-rural-Foret-Chasse/Exploitations-agricoles/Chardon-des-champs-lutte-obligatoire

(2) Verses from Pliny the Elder's Naturalis Historia, Book 21, paragraphs 91-100 https://www.perungiorno.it/plinio-il-vecchio-naturalis-historia-libro-21-paragrafi-91-100.html

(3) The national flower of Scotland. Visit Scotland. https://www.visitscotland.com/it-it/inspiration/culture/thistle

(4) Pasquale Viggiani. The story of the cardoon that changed history. Georgofili INFO. 10.5.23 https://www.georgofili.info/contenuti/la-storia-del-cardo-che-cambi-la-storia/27417

(5) https://powo.science.kew.org/results?q=thistle

(6) Didier Willey. Cardoons: forget their reputation. L’ami des Jardin. Translation by Mariangela Barbiero. http://www.trafioriepiante.it/infogardening/giardino/Cardi.htm#:~:text=I%20veri%20cardi%20appartengono%2C%20come,Sylibum%20(il%20cardo%20mariano)

(7) Luìs R. Silva, Telma A. Jacinto, Paula Coutinho. Bioactive compounds from cardoon as health promoters in metabolic disorders. Foods 2022, 11(3), 336. https://doi.org/10.3390/foods11030336

(8) Dario Dongo, Serena Lazzaro. Bergamot and wild thistle useful to reduce hepatic steatosis. Clinical study. Food Times. 18.9.20

(9) Filipa Mandim, Celestino Santos-Buelga, Isabel C.F.R. Ferreira, Spyridon A. Petropoulos, Lillian Barros. The wide spectrum of industrial application for cultivated cardoon (Cynara cardunculus L. var. Altilis DC.): a review. Food Chemistry, V. 423, 2023, 136275. https://doi.org/10.1016/j.foodchem.2023.136275

(10) Paulina M. Opyd, Adam Jurgoński. Intestinal, liver and lipid disorders in genetically obese rats are more efficiently reduced by dietary milk thistle seeds than their oil. Sci Rep 11, 20895 (2021). https://doi.org/10.1038/s41598-021-00397-1

(11) Fondazione SlowFood. Hunchback thistle of Nizza Monferrato - Slow Food Presidium. https://www.fondazioneslowfood.com/it/presidi-slow-food/cardo-gobbo-di-nizza-monferrato/

(12) Po Piedmont protected areas. Ivory white thistle of Andezeno. https://www.parcopopiemontese.it/dettaglio_prodotto.php?id=3684