- Subspecies: Carlina vulgaris ssp. vulgaris, Carlina vulgaris ssp. longifolia (synonym Carlina biebersteinii)
- Family: Daisy Family – Compositae, subfamily Carduoideae
(formerly Aster Family – Asteraceae)
- Growing form: Biennial or short-lived, once-flowering perennial herb.
- Height: 10–50 cm (4–20 in.). Stem branchless–sparsely branched at top, sturdy (ssp. vulgaris) or quite delicate (ssp. longifolia), usually woolly, reddish.
- Flower: Single flower-like 20–35 mm (0.8–1.4 in.) capitula surrounded by involucral bracts. Capitula’s ray-florets lacking; disc florets yellow–purple, tubular, small. Stamens 5. Pistil of 2 fused carpels. Involucre hemispherical, involucral bracts in many rows, outer bracts leafy, with spiny margins, inner bracts membranous, straw-coloured. Capitula 1–11 (usually 2–5).
- Leaves: In basal rosette and alternate on stem, rosette prostrate (ssp. vulgaris) or quite erect (ssp. longifolia), lower leaves stalked, stalk winged, upper slightly amplexicaul. Blade (narrowly) lanceolate, pinnately lobed–toothed, thick, glabrous, shiny and strong-spined (ssp. vulgaris) or thin, clearly hairy and delicately spiny (ssp. longifolia).
- Fruit: Long, hairy, brown, achene, tip with feathery hairs that break off easily.
- Habitat: Dry hillside meadows, pastures, sometimes road-sides, sea-shores.
- Flowering time: July–August.
- Endangerment: Ssp. vulgaris is vulnerable and ssp. longifolia is endangered. Both are protected in all of Finland including the Åland Islands.
Carline thistle is divided in Finland into two subspecies which differ from each other with regards to appearance and habitat. Ssp. vulgaris grows in south-western Finland and is low-growing, sturdy, spiny and often has at least two capitula. Ssp. longifolia (synonym Carlina biebersteinii) grows in eastern Finland and is rarer, taller, more delicate, sparsely small-spined and often has only a solitary capitulum. Their habitats do not overlap in Finland and they were earlier regarded as two different species.
Both subspecies have become much rarer in recent years as dry, light-filled juniper meadows and land where sheep keep the grass short have become rare. Natural grazing is practiced very rarely on the archipelago nowadays, and the fate of slash-and-burn areas on the mainland looks just as dark. As its traditional environment has become overgrown the species have appeared more often beside roads. Its third habitat is sea shores, which supports the assumption that it is native to the archipelago’s coastal zone.
Ssp. vulgaris has always been most common on the Åland Islands where it still grows quite vigorously. It grows in over 30 different places there, dispersed between the main island and some smaller ones in the archipelago. In the south-west archipelago it can be found mainly on Dragsfjärd, and it also grows in Kemiö. Although both subspecies have disappeared entirely from some areas, if the land is properly tended its seed-bank could be encouraged to show itself. Ssp. longifolia has only 15 places left where it grows in southern parts of Häme and Savo respectively.
Carline thistle blooms for a long time and looks very ornamental. Its capitula only open on sunny days, closing up for the night and staying shut on rainy days. It is pollinated by insects, mainly bumblebees, but self-pollination is probably common. The capitula can also be home to the small butterfly Metzneria aestivella, which is completely dependent on the plant. It was feared that it had become extinct in Finland, but it has been observed to be hanging on on the Åland Islands in carline thistle stands.