Scolymus is a small genus of spiny herbaceous plants in the family Asteraceae (order Asterales), commonly known as golden thistle or oyster thistle. The three species are annuals, biennials, or perennials that grow up to 1¾ m tall, all sharing a characteristic thistle-like appearance with winged, spiny stems and milky latex canals throughout the plant. Flowerheads bear ligulate (strap-shaped) florets that are typically yellow, occasionally orange or white, and all species share a chromosome number of 2n=20.
The genus is distributed across Macaronesia, the Mediterranean Basin, and the Middle East. Scolymus hispanicus (Spanish oyster thistle) has the widest range, extending from northwestern France south to Morocco and east from Ukraine to Iran, and has naturalized in Australia, the United States, Argentina, and Chile. Scolymus maculatus ranges from Britain to the Canary Islands across the Mediterranean eastward to Iran. Scolymus grandiflorus has a more restricted range centered on the western Mediterranean, including Spain, southern France, Italy, and North Africa.
The three species differ in habit and floral detail. S. maculatus is strictly annual, reaching 1½ m, with pinnately divided bracts, black-haired florets, and cypselas lacking pappus. S. grandiflorus is annual or biennial, reaching ¾ m, with spiny-dentate bracts and smooth pappus bristles. S. hispanicus may be annual, biennial, or perennial, reaching 1¾ m, with interrupted spiny stem wings and scabrous pappus bristles.
Etymology
The genus name Scolymus is derived from the Greek σχόλυμος (skolymus), meaning "artichoke." The name was used by the ancient naturalist Pliny for what is now Scolymus hispanicus, and was formally validated by Carl Linnaeus in 1753, who drew on Joseph Pitton de Tournefort's 1700 description. The species epithets are Latin: hispanicus ("from Spain"), maculatus ("spotted"), and grandiflorus ("large-flowered").
Distribution
The genus Scolymus is native to Macaronesia, the Mediterranean Basin, and the Middle East. Scolymus hispanicus has the broadest range, from northwestern France and Morocco east to Ukraine and Iran, and is naturalized in Australia, the United States, Argentina, and Chile. Scolymus maculatus extends from Britain to the Canary Islands across the Mediterranean to Iran, and is naturalized in Australia and North Carolina. Scolymus grandiflorus is confined largely to the western Mediterranean: Spain (including the Balearic and Canary Islands), southern France, Italy, Turkey, Lebanon, and North Africa.
Ecology
Scolymus hispanicus is characteristic of disturbed, open habitats in central Spain, including roadsides, paths, arable fields (both cultivated and fallow), and pastures, where it favors unstable, loose, and nutrient-poor soils. Florets across the genus are insect-pollinated.
History
The genus has a long history in European botany. Carolus Clusius recognized S. hispanicus as early as 1576 under the name Scolimus Theophrasti, and by 1601 had distinguished three taxa corresponding to the three modern species. Earlier synonyms include Carduus Chrysanthemus (Dodoens 1583; Cupani 1713), Spina lutea (Bauhin 1650–51), and Cichorium luteum (Morison 1699). None of these pre-Linnaean names were nomenclaturally valid. The current accepted genus name was established by Linnaeus in 1753.
