- Name also: Nodding Thistle, Nodding Plumeless Thistle
- Family: Daisy Family – Compositae, subfamily Carduoideae
(formerly Aster Family – Asteraceae)
- Growing form: Biennial herb.
- Height: 30–150 cm (12–60 in.). Stem sparsely branched, winged, sharp-thorned, woolly.
- Flower: Flowers form 2–6 cm (0.8–2.4 in.) wide, single flower-like capitula surrounded by involucral bracts. Capitulum lacks ray-florets; disk florets purple (rarely white), tubular. Stamens 5. Gynoecium composed of 2 fused carpels. Involucre semi-spherical, involucral bracts overlap in many rows, tongue-like, long, tapered, with midrib, spine-tipped. Capitula solitary, nodding. Pedicels usually long, wingless, densely white-haired.
- Leaves: Alternate, stalked. Blade lanceolate, pinnately lobed, lobes 6–10, narrow.
- Fruit: Oval, gently curved, glabrous, shiny, light-coloured 3–5 mm (0.12–0.2 in.) long achene with unbranched, 13–24 mm (0.5–1 in.) long hairs on tip.
- Habitat: Ballast soil deposits, harbours, roadsides, waste ground. Calciphilous.
- Flowering time: July–September.
Spiny thistles are very characteristic of coastal Mediterranean sheep and goat pastures. Musk thistle travelled from there in the time of sailing ships, establishing itself in Finland too in ballast soil deposit heaps in a couple of harbours on the Gulf of Bothnia. The only remaining strong stand from those days is on Reposaari in Pori, where the species was first observed at the beginning of the 1870s. In nearby Tahkoluoto musk thistle grew regularly in the same place for 30 years until recently. The species also grew for several decades in Rauma, Kristiinankaupunki and Oulu’s harbour areas, although it would appear to have now disappeared. There is however hope that the species will reappear, e.g. when the earth is disturbed. The last Finnish musk thistle stand has been classed as endangered due to house construction, but with careful planning, care for the plants’ habitat and cooperation with the residents this special looking and highly ornamental species should survive in Finland.
The decrease of musk thistle is unfortunate because its capitulum flowers are among the finest in Finland: up to 6 cm (2.4 in) in diameter, so heavy that the crown begins to nod. Although the plant gathers power for its flowering time throughout the year as a leaf rosette, in the Finnish climate the impressive inflorescence does not grow until the end of the summer. Musk thistle is easy to confuse with its close thistle relatives, although they don’t usually have winged stems. Another clear difference is also the achene’s flying hairs, which are unbranched on genus Carduus plants and feathery on genus Cirsium plants.