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Dandelions and quackgrass aren’t the only weeds a gardener in Calgary needs to look out for – invasive ornamental plants can sometimes disguise themselves as pretty flowers and wreak havoc on our urban and wild landscapes. 

Weeds and plants to watch out for

Invasive ornamentals may look nice, but they choke other desirable garden species, take over flower beds and lawns, and spread rapidly between yards and parks. The province of Alberta regulates weeds under the Weed Control Act in 2 categories: Noxious and Prohibited Noxious.

In Calgary, the Early Detection Rapid Response (EDRR) program aims to prevent the spread of a priority list of invasive weeds through accurate identification and early intervention to minimize long-term environmental impacts and economic costs by targeting invasive species during their initial stage of establishment. These invasive plants not only have serious and unfortunate impacts on your immediate environment - they affect many areas of Calgary's economy and ecology. By encouraging the establishment and spread of these sneaky invaders, we risk:

  • Altering natural plant communities and reducing both animal and plant diversity.
  • Degrading bird, fish and wildlife habitats.
  • Changing water flow, availability and quality.
  • Increasing challenges to food production (including price hikes to compensate for increased weed control.)
  • Potentially reducing the aesthetic, tourism and property values of infested areas within the city.

That's why the City is shining a spotlight on EDRR species Calgarians need to be aware of.

Invasive plants to avoid in Calgary

Scientific Name Common Name(s) and Ornamental Varieties
Scientific Name : Alliaria petiolata (M. Bieb.)   Common Name(s) and Ornamental Varieties :

Garlic mustard, garlic root, garglicwort, hedge garlic, Jack-by-the-hedge, poorman’s-mustard

Scientific Name : Berteroa incana (L.) DC. Common Name(s) and Ornamental Varieties :

Hoary alyssum, hoary false madwort, hoary false alyssum

Scientific Name : Butomus umbellatus L. Common Name(s) and Ornamental Varieties :

Flowering rush, grassy rush, water gladiolus

Scientific Name : Centaurea jacea L. Common Name(s) and Ornamental Varieties :

Brown knapweed, common knapweed, hardheads, brown-ray knapweed

Scientific Name : Centaurea × psammogena Gáyer Common Name(s) and Ornamental Varieties :

Hybrid knapweed

Scientific Name : Cirsium palustre (L.) Scop. Common Name(s) and Ornamental Varieties :

Marsh thistle, marsh plume thistle, European swamp thistle

Scientific Name : Daucus carota Common Name(s) and Ornamental Varieties :

Wild carrot, Queen Anne’s lace, bird’s nest, bishop’s lace, carrot flower

Scientific Name : Fallopia japonica (Houtt.) Ronse Decr. Common Name(s) and Ornamental Varieties :

Japanese knotweed, Asian knotweed, elephant-ear bamboo, fleece flower, Japanese bamboo, wild rhubarb, donkey rhubarb

Scientific Name : Impatiens glandulifera Common Name(s) and Ornamental Varieties :

Himalayan Balsam, policeman's helmet, Himalayan impatiens, ornamental jewelweed, kiss-me-on-the-mountain, Indian touch-me-not, Indian balsam, poor man's orchid

Scientific Name : Iris pseudacorus L. Common Name(s) and Ornamental Varieties :

Pale yellow iris, yellow flag iris, water flag

Scientific Name : Jacobaea vulgaris Gaertn. Common Name(s) and Ornamental Varieties :

Tansy ragwort, Stinking willies, staggerwort, tansy butterweed

Scientific Name : Lepidium appelianum Al-Shehbaz Common Name(s) and Ornamental Varieties :

Globe-podded hoary cress

Scientific Name : Lepidium draba L. Common Name(s) and Ornamental Varieties :

Heart-podded hoary cress

Scientific Name : Lythrum salicaria L. Common Name(s) and Ornamental Varieties :

Purple loosestrife, purple lythrum, spiked loosestrife

Scientific Name : Pilosella aurantiaca L.   Common Name(s) and Ornamental Varieties :

Orange hawkweed, king devil, orange-red king devil, devil’s paintbrush, red daisy flameweed orange paintbrush, orange aster

Scientific Name : Pilosella caespitosa Dumort. Common Name(s) and Ornamental Varieties :

Meadow hawkweed, yellow hawkweed, field hawkweed

Scientific Name : Rhamnus cathartica L. Common Name(s) and Ornamental Varieties :

Common buckthorn, buckthorn, European buckthorn

Scientific Name : Thesium ramosum Common Name(s) and Ornamental Varieties :

Field thesium

If you spot one of these species in Calgary report it on the EDRR Report form.

Learn more about common pests in Calgary​