Cardoon

The wild cardoon is a stout herbaceous perennial plant growing 0.8 to 1.5 m (31 to 59 in) tall, with deeply lobed and heavily spined green to grey-green tomentose (hairy or downy) leaves up to 50 cm (20 in) long, with yellow spines up to 3.5 cm long. The flowers are violet-purple, produced in a large, globose, massively spined capitulum up to 6 cm (2 in) in diameter.[4][5][6][7]

It is adapted to dry climates, native across a circum-Mediterranea area from Morocco and Portugal east to Libya and Greece and north to Croatia and Southern France;[8] it may also be native on Cyprus, the Canary Islands and Madeira.[9] In France, the frost-tender cardoon only occurs wild in the Mediterranean south (Gard, Hérault, Aude, Pyrénées-Orientales, Corsica).[6] It has become an invasive weed in the pampas of Argentina,[7] and is also considered a weed in Australia and California.[10][11][12][13]

The "giant thistle of the Pampas" reported by Charles Darwin has been identified as cardoon.[14]

Cultivated cardoon foliage, Madrid Royal Botanical Garden, without leaf spines.

The two main cultivar groups are the cardoon (Cynara cardunculus Cardoon Group, syn. C. cardunculus var. altilis DC), selected for edible leaf stems, and the artichoke (Cynara cardunculus Scolymus Group, sometimes distinguished as Cynara scolymus or C. cardunculus var. scolymus (L.) Fiori), selected for larger edible flower buds. They differ from the wild plant in being larger (up to 2 m tall), much less spiny, and with thicker leaf stems and larger flowers, all characteristics selected by humans for greater crop yield and easier harvest and processing.[4][15] Wild and cultivated cardoons and artichokes are very similar genetically, and are fully interfertile, but only have very limited ability to form hybrids with other species in the genus Cynara.[4]

The earliest description of the cardoon may come from the fourth-century BC Greek writer Theophrastus, under the name κάκτος (Latin: cactus), although the exact identity of this plant is uncertain.[4] The cardoon was popular in Greek, Roman, and Persian cuisine, and remained popular in medieval and early modern Europe. It also became common in the vegetable gardens of colonial America, but fell from fashion in the late 19th century and is now very uncommon.

In Europe, cardoon is still cultivated in France (Provence, Savoie, Lyonnais), Spain, and Italy. In the Geneva region, where Huguenot refugees introduced it about 1685, the local cultivar Argenté de Genève ("Cardy")[16] is considered a culinary specialty. "Before cardoons are sent to table, the stalks or ribs are blanched tying them together and wrapping them round with straw, which is also tied up with cord, and left so for about three weeks".[17] Cardoons also are common vegetables in northern Africa, often used in Algerian or Tunisian couscous.

Cardoon stalks can be covered with small, nearly invisible spines that can cause substantial pain if they become lodged in the skin. Several spineless cultivars have been developed to overcome this.

Cardoon requires a long, cool growing season (about five months), and while it is not particularly frost-sensitive, in heavier freezes it may lose its leaves and resprout, or in extended hard freezes, die. It also typically requires substantial growing space per plant, so is not much grown except where it is regionally popular.

In cultivation in the United Kingdom, this plant has gained the Royal Horticultural Society's Award of Garden Merit.[18][19]

Cardoons are used as a vegetarian source of enzymes for cheese production. In Portugal, traditional coagulation of the curd relies entirely on this vegetable rennet. This results in cheeses such as the Serra da Estrela and Nisa.

The cardoon is also grown as an ornamental plant for its imposing architectural appearance, with very bright silvery-grey foliage and large flowers in selected cultivars.[7]

Cardoon has attracted recent attention as a possible source of biodiesel fuel. The oil, extracted from the seeds of the cardoon, and called artichoke oil, is similar to safflower and sunflower oil in composition and use.[25] Cardoon is the feedstock for the first biorefinery in the world converting the installations of a petrochemical plant in Porto Torres, Sardinia, providing biomass and oils for the building blocks of bioplastics.

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  Cynara cardunculus - MHNT
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  Young leaves of a spiny wild plant
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  Inflorescence bud
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  Plants
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  Garden plant in bloom
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  Cultivated cardoons in Ágreda, Spain
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  In bloom in a garden near Galveston
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  Cardoon prepared in the Navarrese way
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  Cardoon plant in early August, Botanical Garden, Gaillac
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  A jar of cooked cardoon stalks.
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  A Cynara cardunculus plant at anthesis bearing white flowers
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  Cardoon (Cynara cardunculus) Zaghouan,Tunisia