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Cotton Thistle

Onopordum acanthium

  • Name also: Scotch Thistle, Scottish Thistle, Scotch Cottonthistle
  • Family: Daisy Family – Compositae, subfamily Carduoideae
    (formerly Aster Family – Asteraceae)
  • Growing form: Biennial herb.
  • Height: 50–200 cm (20–80 in.). Stem covered with strong spines, very widely winged, rough, densely white-haired all over.
  • Flower: Flowers form 4–7 cm (1.6–3 in.) wide, single flower-like capitula surrounded by involucral bracts. Capitulum lacks ray-florets, disk florets light purple–red, tubular. Stamens 5. Gynoecium composed of 2 fused carpels. Involucre virtually spherical, involucral bracts narrowly ovate, hard, spine-tipped, hairy. Capitula solitary or in small groups in crown branches.
  • Leaves: Alternate, stalkless, decurrent. Blade ovate–broadly lanceolate, large-toothed lobes, covered in spines, tomentose.
  • Fruit: Grey-brown, black-dotted, 4–5 mm (0.16–0.2 in.) long achene with unbranched, reddish, 7–9 mm (0.28–0.35 in.) long hairs on tip.
  • Habitat: Yards, heaps of earth, roadsides, waste ground, rubbish tips, harbours and ballast soil deposits. Also ornamental.
  • Flowering time: July–September.

Spiny cotton thistle is one of the Nordic Countries’ largest and most strongly-spined herbs. Its large size, densely white-haired stem and leaves and purple capitula also make it one of the most beautiful thistles. Despite its size it is a biennial: the leaf rosette emerges in the autumn and a stout tap root grows and serves as a food store, then in the second year the flowering stem grows. The species follows cultivation and spread to Europe, where it grows in inhabited areas, especially sunny places with rich soil. It favours dry summers that are typical of the Mediterranean area and is a problematic alien in temperate climates. Finland’s cold climate has so far prevented cotton thistle from establishing a firm grip in our nature, although it would appear to have put down firm roots in Sweden. As an alien and on the other hand cultivated ornamental it can be found here and there across almost the whole of the southern half of Finland, in inhabited areas, around buildings and beside roads and coastal banks.

Cotton thistle is also the national flower of Scotland. According to legend, the Scandinavian-born Normans’ landing troops were coming to attack the Scots one night when an unlucky soldier stood on the leaf rosette of a cotton thistle. His cry warned the defenders in time, and the grateful Scots adopted the cotton thistle as the national flower. This good story might have something behind it, but it is also folklore: cotton thistle had not arrived yet in the Middle ages on Scotland’s moors, but thanks to its frightful spines it has been later been chosen as the hero of the tale.

Other species from the same family

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