Onopordum Acanthium
Scotch Thistle  




IDENTIFICATION

Regional Noxious. Biennial or perennial.
Scotch thistle has woody, branched stems with long, spine-edged wings running up the sides. It has numerous, large, bright violet to reddish flowers supported by large spine-tipped bracts. Woolly hairs cover large, irregularly-lobed leaves that have sharp yellow spikes. Mature plants can be up to 3 m tall.

DAMAGE
Scotch thistle can be competitive with desirable native forage plants when it forms dense stands that are impenetrable to livestock. This species can occasionally invade field crops.

HABITAT
In British Columbia, Scotch thistle is found at low elevations along roadsides, irrigation ditches, on rangelands and disturbed areas. The seeds contain a water-soluble germination inhibitor, so it is often successful in moist areas such as riverbanks. It is regarded as a major concern only in the North Okanagan region.

SPREAD
Scotch thistle spreads by seed, mainly on the wind, but also in hay and water, and by attaching to clothing or animal fur.


 

 
Weeds BC home Weeds BC home Resources