T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Carduus tenuiflorus (Winged thistle)

Kingdom:   Plantae
(unranked):        Angiosperms
(unranked):        Eudicots
(unranked):        Asterids
Order:        Asterales
Family:      Asteraceae
Tribe:         Cynareae
Genus:       Carduus
Species:     C. tenuiflorus
Binomial name: Carduus tenuiflorus
Common names:  Winged thistle, Slender-flower thistle, Sheep thistle, Shore thistle, Slender thistle, Winged plumeless
thistle, Winged slender thistle.

Carduus tenuiflorus is an annual species of thistle native to Europe and North Africa. It has spread to other continents, where it is an introduced species and a noxious weed. It is now naturalised in New Zealand and is a tenacious weed of roadsides, fields, and disturbed areas. It is common throughout both the North and South Islands, but not in Westland.

Carduus tenuiflorus is a winter annual, which means most seeds germinate in autumn. In winter grows from seeds that have lain in the soil over summer. It first grows as a tap-rooted rosette. In this vegetative stage, it has the typical prickly rosette of a thistle species, though it tends to have some faint whitish venation in the leaves. In spring it develops an upright flower stem. The stem is erect and has spines that may be several cms in length. The stem is branched, winged and at the top is a dense inflorescence of three to eight stalkless, smallish (up to 1.5 cm wide) flower heads develop between November and December. The inflorescences may hold up to 20 flower heads with pale pink to bright purple long tubed disc florets. The pappus filaments of ar winged thistle tend to be about 10 - 12 mm long.
The leaves are a dull olive-green and are spiny, deeply lobed and up to 30 cm long by 15 cm wide. The upper surface is green and the underside has white tomentum.
The plants usually dies in late summer, unlike other thistles that have plants present through the summer months. Because of this die off winged thistles are well suited to invade pastures that are prone to drying out in summer. 

The thistle rosette

White form

The purple form

Plant early December 

The winged stem

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/