Spotted Knapweed
Centaurea stoebe • Class B |
||
Family Name: | Asteraceae family (ass-ter-AY-see-ee) | |
Common: | Aster, daisy, or sunflower family | |
Genus: |
Centaurea (sen-TAR-ee-uh) Meaning: Latin, referring to the Centaur Chiron who discovered the medicinal use of the Centaury plant |
|
Species: |
stoebe (sto-bee) |
Description: |
Spotted knapweed grows up to 5 feet tall and has a thick tap root. Plants form basal rosettes during winter and early spring and develop highly branched flowering stems in late spring and summer. Its alternate, pale grayish-green leaves are egg-shaped to oblong, and are once or twice divided and covered with hairs. Numerous pink to purple flowers (sometimes white) dot the tops of this bushy plant from May to September. It is easily identified by the egg-shaped bracts at the base of each flower. Bracts look spotted due to their dark colored, triangle shaped tips, with a comb-like fringe. Its brown/black oval seeds have short bristles (pappus) on one end. |
Why Is it a Noxious Weed? |
This is a very aggressive species. It can infest large areas very quickly. The species has little value as forage for cattle and increases production costs for ranchers. It impairs the quality of wildlife habitat, decreases plant diversity, increases soil erosion rates on valuable watershed areas, and poses a wildfire hazard. |
Where Does it Grow? |
It is found along roads, railroads, gravel pits, vacant lots, pastures, dry meadows and fields, and forest clearings. |
Facts: |
Spotted Knapweed contains Sesquiterpene lactones (SQL) a class of chemicals found in many plants, which can cause allergic reactions and toxicity if consumed in large quantities, particularly in grazing livestock. These lactones are known to inhibit germination and root growth of nearby native grasses, trees, and weeds. |
Control Options: |
|
More Information: |
Download our Flyer or visit Washington State Noxious Weed Control Board Here. Photo by Leo Michels
|
More Pictures: |