Melancholy thistle

Carduus helenioides Linnaeus, Sp. Pl. 2: 825. 1753; Cirsium heterophyllum (Linnaeus) Hill

Perennials, 40–120 cm; runner roots. Stems single, erect, ± arachnoid-tomentose; branches 0 or few, ascending. Leaves oblong to broadly lanceolate, 20–40 × 4–8 cm, finely spinulose-dentate or proximal cauline pinnatifid, lobes undivided, finely spinulose-dentate, main spines 1–2 mm, abaxial faces white-tomentose (with non-septate trichomes), adaxial glabrous; basal present at flowering, petiolate, bases tapered; cauline sessile, reduced distally, bases clasping, not decurrent; distal (few, well separated), oblong or linear, the uppermost reduced to linear bracts. Heads borne singly or less commonly 2–5 in terminal clusters. Peduncles 2–10(–30) cm (elevated above distal leaves). Involucres broadly ovoid, 2–3 × 2–3.5 cm, glabrous or loosely arachnoid. Phyllaries in 8–10 series, imbricate, green, ovate or lanceolate (outer) to linear-lanceolate (inner), abaxial faces with a prominent elongate glutinous ridge, outer and middle tightly appressed, margins entire, apices with ascending, weak spines 0–1 mm; apices of inner phyllaries attenuate, flat. Corollas red-purple, 25–30 mm, tubes 10–23 mm, throats 8–14 mm (noticeably wider than tubes. , lobes 7–10 mm; style tips 4–5 mm. Cypselae light brown, 3–5 mm, bodies and apical collars concolorous; pappi 20–30 mm. 2n = 34.

Flowering summer (Jul–Aug). Fjordlands; 0–50 m; of conservation concern; Greenland; Iceland; Europe; Asia.

Cirsium helenioides is one of only two species of the genus that have native populations in the Old World and the flora area. Neither reaches the North American mainland.

The conservation status of Cirsium helenioides is not known; it is known in the flora area only from a single fjord and possibly should be considered of conservation concern.