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
Conservation status
Not applicable
Habitat
Terrestrial.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland).
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs in uplands (non-wetlands).
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).