Invasive Weeds

Prohibited Noxious Weeds Found in the M.D. of Wainwright

Prohibited Noxious weeds pose a serious threat and must be eradicated. These weeds spread rapidly and are highly competitive. Weeds in this category are restricted to prevent establishment in Alberta.

Hoary Alyssum

Key Features: Greyish-green leaves with star shaped hairs; white, small, deeply notched petals on slender stalks, sepals hairy

Spotted Knapweed

Key Features: deeply lobed, “cobwebby” basal leaves; generally purple flowers; oval bracts with a black-tipped fringe

Nodding Thistle

Key Features: winged prickles along the stem, except below flower heads; large, nodding, purple flower heads; involucral bracts spine-tipped and bent backwards


Diffuse Knapweed

Key Features: Stems are upright, highly branched, and angled, with short, stiff hairs on the angles; Flowers solitary or in clusters of 2-3 at the end of the branches; Heads contain two types of flowers, ray flowers around the edges surrounding tubular disk flowers; Unlike other knapweeds the heads of the diffuse do not open to the shed seeds


Himalayan Balsam

Key Features: Bamboo-like stem, smooth, usually hollow and jointed; Red tinged stem and leaves; Sharply serrated leaves; Opposite or whorled leaves, usually 3; Exploding fruit capsules


Orange Hawkweed

Key Features: Rosette leaves are narrow, spatula shaped, hairy, 10-15cm long, and darker green on the upper surface.

Noxious Weeds Found in the M.D. of Wainwright

Noxious Weeds have the ability to spread rapidly, cause severe crop losses and economic hardship. These weeds must be controlled to prevent further establishment and spread.

Common Baby’s-breath

Key Features: Opposite and lance shaped leaves; numerous branches; numerous small white flowers with 5 petals

Downy Brome

Key Features: Leaf blades are 2-4 mm wide, 5-12 cm long covered with soft hairs; often reddish-purple when mature, covered with soft hairs, long awns

Great & Lesser Burdock

Key Features: Large heart-shaped leaves, wooly nderneath; clusters of purple-pink flowers

Scentless Chamomile

Key Features: Finely-divided leaves; noticeable lack of odor; daisy-like heads at full maturity resemble a badminton shuttlecock

Yellow Clematis

Key Features: Leaf tips are pointed and edges are coarsely toothed; flowers are yellow with 4 petals, bell shaped

White Cockle

Key Features: opposite, softly hairy leaves; swollen nodes; large, white, showy flowers; capsule opening by ten teeth

Oxeye Daisy

Key Features: short, creeping roots; spoon-shaped, coarsely-toothed basal leaves; strong, unpleasant odor

Leafy Spurge

Key Features: white latex in all parts of the plant; deep and spreading roots with buds; greenish-yellow bracts underneath the flower groupings

Common Tansy

Key Features: Short rhizomes; fern-like, aromatic leaves; yellow, button-like heads in clusters

Canada Thistle

Key Features: Alternate, wavy, lance shaped, lobed, spine-tipped and lack stalks; purple fading to white flowers

Yellow Toadflax

Key Features: found in patches due to creeping roots; crowded, linear leaves that are narrower at each end; bright yellow and orange flowers that are “snapdragon-like”



Key Features: Grows erect, 30-100cm; Lower and middle leaves are similar in appearance; Leaf bladed deeply lobed but not completely divided into 3-5 sections; Distinct leaf stalks, flattened and partly surrounding stem.