 Short-fringed knapweed
Centaurea nigrescens Willd.
Family: Asteraceae 
Description and Life Cycle:
Short-fringed knapweed is a taprooted, herbaceous
perennial that measures 30 – 150 cm tall. The plants can have one or
several openly branching erect stems and can be smooth or sparsely
hairy. Basal leaves are broadly elliptical-shaped, measuring 5 – 15
cm long and up to 3 cm at their widest point. They have smooth
margins, deep to shallow lobes or irregular pinnate cuts. Basal
leaves may also be smooth or lightly hairy on their undersides. Stem
leaves are lanceolate shaped and lack stalks and gradually become
smaller moving up on the plant. Flowers are present from June
through September. The blossoms are pink-rose coloured (rarely
white), 1.5 – 2.0 cm across and arise from a rounded, egg-shaped
base. Individual bracts widen at the upper tips and have dark
coloured (almost black), tattered or comb-like spines. The lighter
areas of the bracts are not completely covered by the dark spines,
which give the plant a ‘spotted look’. Seeds are tan coloured, 2.5 –
3.0 mm long with fine hairs. Pappus is absent or limited to many
irregular bristles 0.5 – 1.0 mm long. Each seedhead produces 22 to
44 seeds.
Note: Short-fringed knapweed is often confused with black knapweed.
Biological Control Agents
References
Douglas, G. W., G. Stranely, D. Meidinger and J. Pojar, eds. 1998. Illustrated flora of British Columbia. Volume 1. Gymnosperms and Dicotyledons (Aceraceae through Asteraceae). Govt. of BC., Min. Environ. Lands and Parks and Min. For.
Flora of North America. 2007. 9. Centaurea nigrescens Willdenow, Sp. Pl. 3: 2288. 1803. November 9, 2007. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023639
MFR staff observations and comments
Tyrol Knapweed (Centaurea nigrescens Willd.). 2003. Nearctica.com, Inc. 2008-02-06. http://www.nearctica.com/flowers/composit/thistle/centaur/Cnigres.htm
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