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May is BC Invasive Species Action Month! learn more »

100 Positive Actions in 1 Day

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Webinar Recording

Calling all gardeners - watch the Bringing Back the Natives Garden Tour webinar.recording learn more »

June 27 Webinar

e-Learning for Realtors and Landscape Architects learn more »

Courses across BC March - May 2018

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Watch the recording

Learn about the potential economic impacts of a new BC invasion learn more »

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Presented by Dr. Jon Bossenbroek, University of Toledo. learn more »

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Parrot's Feather

A popular aquatic garden plant that spreads with water currents, animals, boats/trailers and fishing gear. Dense stands can stagnate water, and increase breeding grounds for mosquitoes learn more »

Zebra/Quagga Mussels

These tiny freshwater mussels clog drains, damage infrastructure, and are very costly to control/eradicate learn more »

Giant Hogweed

A towering toxic invasive plant with WorkSafe BC regulations learn more »

European Fire Ant

A tiny ant with a toxic sting learn more »

Purple Loosestrife

An aggressive wetland invader that threatens plant and animal diversity learn more »

Orange Hawkweed

Also yellow, these invasive plants replace native vegetation along roadsides, and threaten areas not yet reforested learn more »

Japanese Knotweed

Grows aggressively through concrete, impacting roads and house foundations learn more »

Spotted Knapweed

A single plant spreads rapidly with up to 140,000 seeds per square metre learn more »

Scotch Broom

An evergreen shrub that invades rangelands, replaces forage plants, causes allergies in people, and is a serious competitor to conifer seedlings learn more »

Scotch Thistle

Species
Onopordum acanthium

Scotch thistle (Onopordum acanthium) is a biennial or perennial plant that can form dense, inpenetrable stands and competes with field crops and forage plants.

Considered regionally noxious under the BC Weed Control Act, Scotch thistle is a major concern in the North Okanagan region, and otherwise occurs at the lower elevations of BC's roadsides, irrigation ditches, rangelands and disturbed areas. Scotch thistle continues to be grown in gardens around BC. There is concern that impacts will increase as it escapes controlled garden environments and invades natural areas.

Growing up to 3 m tall, Scotch thistle is identifiable by its large, bright violet to reddish flowers that are supported by large spine-tipped bracts. Woody stems also have spine-edged wings that run up the sides. Leaves are irregularly-lobed, have sharp yellow spikes, and are covered in woolly hairs that give the foliage a grey-green appearance.

Scotch thistle reproduces through thousands of seeds that remain viable in the soil for over 30 years. Seeds spread mainly with the wind, but also in hay and water, and by attaching to clothing or animal fur. Seeds also contain a water-soluble germination inhibitor, making it successful in moist areas such as nearby streams and in riparian areas.

Gallery: Scotch Thistle