Cirsium palustre (L.) Scop.

Fibrous-rooted biennial. Stems not branched, or branched above, with soft scattered multicellular and fine cobwebby hairs, (20)–80–150–(200) cm tall, ribbed, with coarsely spiny wings between lf bases; branches slender. Lvs oblanceolate to narrowly elliptic, shallowly to deeply pinnatifid, green above, paler beneath, (5)–10–25–(35) × (1.5)–3–8–(15) cm, with sparse soft multicellular hairs above and beneath, often also with sparse to dense cobwebby tomentum beneath; lf lobes narrowly deltoid to linear; prickles pale, 2–10 mm long; uppermost lvs becoming smaller. Capitula cylindric to narrowly ovoid at flowering, erect, 1.2–1.5 × 1 cm, in clusters of up to 10; peduncles 0–1 cm long. Outer involucral bracts deltoid to ovate, with cob webby hairs; apex acuminate, with weak spine 1–(2) mm long, suberect. Inner involucral bracts linear, ciliate; apex acute, not spinous, suberect. Corolla magenta, 11–12 mm long; lobes 3.5–4–(5) mm long. Style slightly exserted beyond corolla lobes. Achenes pale, narrowly obovoid, 3–3.5 × c. 1 mm; pappus 8–12 mm long; cilia on pappus bristles 1–2 mm long.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: (Oct.)–Nov.–Feb.–(May); Fruiting: Nov.–Mar.– (May)