Flora of New Zealand Series

marsh thistle

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.

N.: throughout; S.: Westland, Canterbury (Weka Stream and local in the W.), Otago (Owaka), Southland.

Eurasia 1911

Riverbeds, damp pasture, pakihi, roadsides, swampy land, forest margins, coastal gravels, waste land.

FL (Oct)-Nov-Feb-(May), FT Nov-Mar- (May).

The slender, winged, brittle stems, reduced upper cauline lvs and small clustered subsessile capitula with magenta florets give marsh thistle a distinctive appearance. Among the Cirsium spp. in N.Z. the short pappus is only matched in ♂ plants of C. arvense. C. palustre has also been referred to in N.Z. as Carduus palustris and as Cnicus palustris.