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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

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 »

Invasive Species Research Conference

Turning Science into Action! Co-hosted by Thompson Rivers University and the Invasive Species Council of BC. 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 »

Canada Thistle

Species
Cirsium arvense

Canada thistle (Cirsium arvense) is a root-creeping perennial. Thickets of thistle crowd out forage grasses in pastures and rangelands, reducing crop yields and productivity. 

Considered noxious under the BC Weed Control Act, Canada thistle is commonly found on roadsides, cultivated fields, pastures, logged forests, riverbanks, and other disturbed areas. It is a major concern in the Peace River, Omineca and Skeena areas, and is a widespread throughout the province.

Canada thistle has purple or white flowers, with stalkless, spiny, dark-green leaves, growing to 0.3-2 metres in height at maturity.

Canada thistle spreads rapidly through horizontal roots that give rise to large infestation patches nearby and out-competing native plants. Canada thistle develops seeds sparingly and may produce 1,000 to 1,500 seeds per flowering shoot. Best adapted to rich, heavy loam, clay loam, and sandy loam, it grows poorly in shaded conditions, can tolerate saline, wet, or dry soils, but does not tolerate waterlogged or poorly aerated soil. Dispersed primarily by wind, seeds can also be dispersed by water, animals, clothing, equipment, and vehicles. 

TIPS Factsheets

Gallery: Canada Thistle