Globe artichoke
The immature flowering heads and leaf stalks of the globe artichoke and cardoon thistles have been actively cultivated, domesticated, bred and consumed for centuries. Globe artichokes are familiar as large, green-purple, scaly heads. Two parts of these inflorescences are usually eaten freshly cooked or preserved in oil: the fleshy bases of the involucral bracts and the fleshy receptacle upon which the tiny flowers sit. In the case of cardoons, young leaf stalks are usually blanched like celery and eaten raw or cooked.
Whether wild cardoons, cultivated cardoons and globe artichokes are three species or variants of a single species has been the subject of decades of argument. The current view is they are one species of three variants.
Wild cardoon, the ancestor of both globe artichokes and domesticated cardoons, is a very spiny thistle-like plant distributed through open habitats from Macaronesia in the west, along the north and south coasts of the Mediterranean, to the Black Sea in the east.
Compared to wild cardoons, domesticates have few spines, and have been subject to different selection pressures. Globe artichokes have been selected for large flower heads; cardoons have been selected for huge leaves. Furthermore, globe artichokes are vegetatively propagated, i.e., they must be grown from offsets, whilst cardoons are propagated by seeds. One consequence of these reproductive differences is that there is high varietal diversity in globe artichokes but virtually none in cardoons.
Confusion over how Ancient Greeks and Romans applied common names for thistle-like plants makes unpicking classical literature references to thistles, globe artichokes and cardoons difficult. Until recently the view was that cardoons were known to classical authors, whilst artichokes only became well known from the sixteenth century. More recently, reinterpretation of the historical evidence has turned the argument around; artichokes were probably selected from wild cardoons in Sicily towards the start of first millennium CE and moved through the Mediterranean region via trade, whilst cardoons were domesticated in the first half of the second millennium CE in the western part of the wild species' range.
Europeans have taken globe artichokes and cardoons around the world; in some areas they have become weeds. An early report of weediness came from Charles Darwin exploring the Banda Oriental (Uruguay) in 1833. He reported 'immense beds of ... cardoon: the whole country, indeed, may be called one great bed of these plants. ... The cardoon is as high as a horse's back'.
Further reading
Sonnante G et al. 2007a. The domestication of artichoke and cardoon: from Roman times to the genomic age. Annals of Botany 100: 1095-1100.
Sonnante G et al. 2007b. On the origin of artichoke and cardoon from the Cynara gene pool as revealed by rDNA sequence variation. Genetic Resources and Crop Evolution 54: 483-495.
Wiklund A 1992. The genus Cynara L. (Asteraceae-Cardueae). Botanical Journal of the Linnean Society 109: 75-123.
Stephen Harris