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

 

Spotted Knapweed
Centaurea stoebe L. ssp. micranthos (Gugler) Hayek (Aster family, Asteraceae)
 

Description

Multi-branched biennial or short-lived perennial forb, 39 inches tall, with spiny or comb-like flower head bracts; stoutly taprooted; plants exist as basal rosettes until erect, highly branched flowering stems are produced in late spring/summer.

Leaves: Cotyledons spatulate to oval; rosette leaves pinnate- divided without straw-colored spines at their centers; leaves alternate, resin-dotted, lower stem leaves deeply 1 to 2 pinnate-lobed, 4 to 8 inches long; upper stem leaves wingless, mostly pinnate-divided, 3/8 to 3/4 inch long. Foliage variously covered with short to medium interwoven gray hairs; new leaves green and covered with minute bristly hairs.

Flowers: Flowers June to October; 1/4 to 1/2 inch diameter flower heads, solitary or several with 30 to 40 white, pink or purple flowers per head, 1/2 to 1 inch long; pale green or pink-tinged flower head bracts overlapping in several rows, 5/8 to 3/4 inch long, tips dark, comb-like, not spine-tipped.

Fruit: Pale brown achenes oblong, 1/8 to 3/16 inch long, finely hairy, apex flattened and tapered to a rounded, laterally notched base; pappus bristles less than 1/8 inch long.

Habitat

Cultivated and disturbed or degraded sites in meadows and grasslands within elevations that generally range below 7,000 feet.

Propagation/Phenology

Reproduces by seed, up to 40,000 per plant; germination occurs over a broad range of environmental conditions; in addition to seeds, spotted knapweed can reproduce vegetatively from lateral roots just below the soil surface.

Comments

Native to Europe; spotted knapweed is a very competitive and aggressive plant with allelopathic effects; stands of spotted knapweed may persist indefinitely once established. Arizona prohibited/restricted noxious weed and New Mexico Class A noxious weed.

Collage of images of Spotted Knapweed

 

Forest Service Shield
Invasive plants and weeds of the national forests and grasslands in the southwestern region
Spotted Knapweed flower head Spotted knapweed dried bracts and flower heads Spotted knapweed plants Spotted knapweed foliage