Canada Thistle
Cirsium arvense
Sunflower family
Where is it from?
- Canada thistle is native to Europe.
Where are you likely to find it?
- Along wet roadsides, in ditches, in wet meadows and
in wet or compacted pastures.
What makes it a "BAD" plant?
- Canada thistles produce millions of wind-dispersed seed.
- Plants rapidly colonize areas of disturbed ground,
especially in wet areas.
- They are perennial, and once established, they tend to
persist for years to the exclusion of other herbaceous plants.
- Thistles make human and wildlife access difficult, if not
painful.
How do you get rid of it?
- Plants are pulled or dug out of the ground.
- Pulled plants are bagged and removed from the site. Flower
heads after pulling. If not removed, the seed heads would
mature and seeds blow free. Some would germinate, spreading
the plants.
- Repeated follow-ups are needed to remove all of the
underground parts.
- Prevention is the most cost effective approach. After any
type of ground disturbance, quickly seed with desirable
species to minimize the opportunity for Canada thistle
to become established.
What can you do to help?
- Report sightings. If in other parks, contact the
Superintendent. If in the Redwood National and State
Parks, notify the Vegetation Management branch at the
South Operations Center in Orick (707-464-6101, ext. 5282).
Tell them about the location of the plants so they can be
mapped for future work projects.
- To become even more involved in control of this and other
exotic species, sign up as a Volunteer
in Parks (VIP).
- CAUTION: Do not remove plants without permission
in writing or direction from a private land owner,
manager or, if on public lands, an agency official.
