Invasive Species Council of Manitoba
Scotch Thistle
Onopordum acanthium
Scotch Thistle is a biennial that was introduced from Eurasia. It competes with desirable native forage species and forms dense stands that can become impenetrable to livestock; it can even invade field crops.
This plant can be found along roadsides, disturbed areas, irrigation ditches, disturbed habitat and on range lands.
It even does well in riparian areas because it has a water soluble germination inhibitor that prevents other plants from growing.
The stem can grow 1.5 -3 m tall, there are numerous branches and it's covered in woolly hair. Leaves are large and irregularly lobed and covered with sharp spikes. A single plant can produce a70-100 purple to red flowering heads that have spine tipped bracts.
Each flower can produce 100-140 seeds which can remain viable in the ground for over 30 years. Seeds are mostly dispersed by wind but can be spread by attaching to clothing or fur or being transported in hay machinery or via water ways.
Information provided by Weeds BC
Resources
2011 Rural Municipality Distribution Map
2010 Rural Municipality Distribution Map
Scotch Thistle MWSA 2009 Survey Map
CURRENT NEWS:
ISCM hosts an AGM annually where members are invited to participate in the meeting.
More details to be announced soon!
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