- Family: Daisy Family – Compositae, subfamily Carduoideae
(formerly Aster Family – Asteraceae)
- Growing form: Perennial herb.
- Height: 40–120 cm (15–50 in.). Stem wingless, spineless, lower part glabrous, upper part short-haired, light.
- Flower: Single flower-like capitula, 1.5–2.5 cm (0.6–1 in.) long, surrounded by involucral bracts. Capitulum lacks ray-florets; disk florets light yellow, tubular. Stamens 5. Gynoecium composed of 2 fused carpels. Involucre cylindrical, involucral bracts erect, lanceolate, thin-spined. Capitula 2–6, solitary–small groups, stalked.
- Leaves: Alternate, stem leaves amplexicaul, ovate. Blade broad, thin, virtually pinnately lobed, margin small-toothed, teeth thin-spined, virtually glabrous on top, lime green. 2–10 ovate, entire upper leaves under capitula.
- Fruit: Flattish, blunt, 4–5.5 mm (0.15–0.22 in.) long achene crowned by a pappus of branched, feathery hairs.
- Habitat: Ditch banks, damp meadows, shores, waste ground, harbours. Also ornamental.
- Flowering time: July–September.
Cabbage thistle grows in damp meadows, ditches and other rich soils. It is common already in Estonia but has yet to establish a good foothold in Finland. In southern and central Finland it’s a rare established alien, while solitary specimens can be found in the north in Kuusamo.
Like its relatives, cabbage thistle’s spines are actually so soft that they don’t deter cattle. This lack of prickliness also makes them suitable for the flower bed. Thistles are among the most handsome plants in Finland, but species that grow here are too common along roadsides to be valued in the garden. Stronger-spined thistles can jag the gardener, which probably partly explains these plants’ unpopularity in gardens. The nectar in thistles’ flowers is quite deep at the end of a long tube so it tempts insects with a long proboscis, e.g. beautiful monarch butterflies.
Most thistles have red flowers although there are forms with a white corolla and a bright green stem. Cabbage thistle however has the special feature of being pale yellow. The capitula surrounds a group of cordate upper leaves, which attract insects.