Cirsium arvense
Common name
Californian thistle
Family
Asteraceae
Flora category
Vascular – Exotic
Structural class
Herbs - Dicotyledonous composites
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
CIRARV
Habitat
Terrestrial.
Features
Rhizomatous perennial often forming large patches. Stems branched above; 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 leaf bases. Leaves lanceolate, pinnatifid, green above, pale beneath, (2)-4-15 x 1-5cm, glabrous or with cobwebby hairs; lobes deltoid to lancolate; prickles pale, 5-10mm long. Capitula narrowly ovoid to cylindric at flowering, erect, 1.5-2-(2.5) X 0.7-1.5-(2) cm in cymes or cymose panicles; peduncles 5-40 mm long. Outer involucral racts linear, ciliate; apex acute, not spinous, erect. Corolla usually pale purple or mauve, sometimes white, 12-18mm long; lobes c. 3mm long. Style slightly exerted beyond carolla lobes. Achenes pale, cylindric, 3-4 X 1-1.5 mm; pappus 20-25 mm long, shorter in male; cilua on pappus bristles 2-3 mm long. (Webb et al., 1988).
Flowering
December, January, February
Flower colours
Red/Pink, Violet/Purple
Fruiting
December-April
Year naturalised
1878
Origin
Eurasia
Etymology
cirsium: A kind of thistle
arvense: Growing in arable fields
Reason For Introduction
Accidental
Life Cycle Comments
Perennial. (Webb et al., 1988).
Reproduction
Rhizomatous (Webb et al., 1988). Almost completely dioecious: female plants do not produce viable pollen but male plants occasionally set a few seeds (Webb et al., 1988).