Pink, Rose, Red, or Purple Flowered Forbs

Pink, Rose, Red & Purple Flowered Forbs
Alfalfa
Black henbane
Blue Mustard
Bull thistle
Canada thistle
Common burdock
Diffuse knapweed
Hounds-tongue
Iberian knapweed
Meadow knapweed
Musk thistle
Purple loosestrife
Purple starthistle
Red clover
Redstem filaree
Russian knapweed
Scotch thistle
Spiny plumeless thistle
Spotted knapweed
Squarrose knapweed
Tall morning-glory
Teasel

 

Canada Thistle
Cirsium vulgare (Savi) Ten. (Aster family, Asteraceae)
 

Description

Erect clump or patch-forming perennial forb to 39 inches tall, with extensive creeping roots and small unisexual flower heads; plants are male or female (dioecious), and dense patches of a single sex often occur; foliage and stems are spiny.

Leaves: Rosette leaves few or lacking; all leaves oblong to lanceolate, 2 to 8 inches long; margins nearly entire to shallowly lobed and toothed; main prickles 1/8 to 1/4 inch long; upper surfaces glabrous, green; lower surfaces sometimes sparsely woolly; leaf bases sometimes extend briefly down stems as inconspicuous prickly wings to 3/8 inch long; spiny stems slender, glabrous, and leafy.

Flowers: Flowers June to October; cylindrical or ovoid to bell- shaped unisexual flower heads numerous, often clustered; flower head bracts 3/8 to 1 inch long, 3/16 to 3/4 inch diameter, often, glabrous or with white woolly hair, spines 1/16 inch long; flowers pink, purple, or white (males 3/8 to 9/16 inch long, females 9/16 to 3/4 inch long).

Fruit: Achenes 1/16 to 1/8 inch long, ovate to elliptic, slightly compressed, smooth, glossy, tan; pappus bristles plumose and deciduous, 9/16 to 3/4 inch long, tan, forming a ring at the base and falling as a unit.

Habitat

Cultivated and disturbed or degraded sites in moist grassland, woodland, forest and riparian communities, and roadsides within elevations that generally range from 4,200 to 8,300 feet.

Propagation/Phenology

Reproduces vegetatively from creeping roots and by seed; root reserves are lowest when flowering begins in early summer; new roots and shoot buds develop in winter, and shoots emerge in spring; subterranean shoots can develop roots and buds at any node; root and subterranean shoot fragments 3/8 inch long or more can develop into a new plant; female plants only produce viable seed if male plants
are within pollinator range.

Comments

Native to Europe; heavy grazing and disturbances that create bare soil patches facilitate seedling establishment and survival. Arizona prohibited noxious weed, New Mexico Class. A noxious weed, and Oklahoma noxious weed.

Collage of 4 images of Canada thistle

 

 
Forest Service Shield
Invasive plants and weeds of the national forests and grasslands in the southwestern region
Canada thistle maile flower heads Canada thistle female flower heads Canada thistle foliage Canada thistle plants