Scientific Name:
Cirsium arvense (L.) Scop. (1772)
Vernacular Name(s):
Californian thistle; cally thistle; Cally thistle (NZ); Perennial thistle

Rhizomatous perennial often forming large patches. Stems branched above, with multicellular eglandular and fine cobwebby hairs below, becoming glabrous above, (20)–40–100–(150) cm tall, ribbed, not winged or sometimes with a spiny wing 0–1–(2) cm long decurrent from lf bases. Lvs lanceolate, pinnatifid, green above, pale beneath, (2)–4–15 × 1–5 cm, glabrous or with cobwebby hairs; lobes deltoid to lanceolate; prickles pale, 5–10 mm long. Capitula narrowly ovoid to cylindric at flowering, erect, 1.5–2–(2.5) × 0.7–1.5–(2) cm, in cymes or cymose panicles; peduncles 5–40 mm long. Outer involucral bracts lanceolate, cobwebby-ciliate; apex acuminate, with weak spine 1–(2) mm long, suberect. Inner involucral bracts linear, ciliate; apex acute, not spinous, erect. Corolla usually pale purple or mauve, sometimes white, 12–18 mm long; lobes c. 3 mm long. Style slightly exserted beyond corolla lobes. Achenes pale, cylindric, 3–4 × 1–1.5 mm; pappus 20–25 mm long, shorter in ♂; cilia on pappus bristles 2–3 mm long.

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


Flowering: Dec.–Feb.–(Apr.); Fruiting: Dec.–Apr.

Biosecurity New Zealand 2012: Regional Pest Management Strategies Database.
Howell, C. 2008: Consolidated list of environmental weeds in New Zealand. DOC Research & Development Series 292: 42.