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Species
Centaurea stoebe subsp. micranthos (Gugler) Hayek 1931
IUCN
NCBI
EOL Text
Spotted Knapweed is common in NE and east-central Illinois, and occasional to absent elsewhere within the state. Official records undoubtedly underestimate the distribution of this plant; it is probably still spreading. Habitats include gravelly areas along roadsides and railroads, dry waste areas and eroding slopes, pastures and abandoned fields, and vacant lots in cities. This plant occurs in disturbed areas primarily; sometimes it is found along the edges of prairie remnants near railroads. In some of the Western states, Spotted Knapweed has become a serious weed, but it is less of a problem in Illinois. This species is adventive from Eastern Europe and the Ukraine, and first appeared in the United States and Canada during the 1890's.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2002-2014 by Dr. John Hilty |
Source | http://www.illinoiswildflowers.info/weeds/plants/sp_knapweed.htm |
The most cost effective management strategy for spotted knapweed is to prevent its spread to non-infested areas. Spread by seed can be minimized by avoiding travel through infested areas by: 1) cleaning footwear, clothing, backpacks, and other items after hiking through infested areas; 2) not grazing livestock when ripe seeds are present in the flower heads; and 3) using certified weed-free hay. Individual plants can be pulled by hand when the soil is moist as long as the entire crown and taproot are removed, using a shovel or weed-popper type tool if necessary. Control of spotted knapweed infestations is very difficult and may require large investment of time, labor and materials to remove using manual and mechanical means or repeated applications of herbicides often at higher rates.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | U.S. National Park Service |
Source | http://www.nps.gov/plants/alien/pubs/midatlantic/cestm.htm |
Canada
Origin: Exotic
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
United States
Origin: Exotic
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
The preference is full sun, mesic to dry conditions, and a poor soil that contains gravel or clay; alkaline soil is tolerated quite well. Both the foliage and roots of this species exude a powerful toxin that can destroy the root systems of other plants. This is one of the reasons it often forms colonies.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2002-2014 by Dr. John Hilty |
Source | http://www.illinoiswildflowers.info/weeds/plants/sp_knapweed.htm |
Spotted knapweed is a widely distributed species reported to occur throughout Canada and in every state in the U.S. except Alaska, Georgia, Mississippi, Oklahoma and Texas (see map). It has been designated as a noxious weed in Arizona, California, Colorado, Idaho, Minnesota, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming.
It has been identified as invasive in natural areas by eighteen organizations in twenty-six states (Arizona, California, Colorado, Connecticut, Delaware, Kentucky, Idaho, Illinois, Massachusetts, Maryland, Michigan, Minnesota, Montana, North Carolina, New Jersey, New York, Oregon, Pennsylvania, South Dakota, Tennessee, Utah, Virginia, Washington, Wisconsin, West Virginia, and Wyoming). Fifteen national parks also identify spotted knapweed as an invasive plant and a threat to natural habitats.
Spotted knapweed infests a variety of natural and semi-natural habitats including barrens, fields, forests, prairies, meadows, pastures, and rangelands. It outcompetes native plant species, reduces native plant and animal biodiversity, and decreases forage production for livestock and wildlife. Spotted knapweed may degrade soil and water resources by increasing erosion, surface runoff, and stream sedimentation. It has increased at an estimated rate of 27% per year since 1920 and has the potential to invade about half of all the rangeland (35 million acres) in Montana alone.
Central Europe, east to central Russia, Caucasia, and western Siberia
Spotted knapweed invades a wide variety of habitats including open forests, shale, serpentine and other barrens, meadows, prairies, old fields, and disturbed areas. It forms deep taproots allowing it to capture moisture and nutrients and spreads rapidly, displacing native vegetation and reducing the forage potential for wildlife and livestock.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | U.S. National Park Service |
Source | http://www.nps.gov/plants/alien/pubs/midatlantic/cestm.htm |
Spotted knapweed is widely distributed in the U.S. and is reported to occur in every state in the Lower 48 except Texas, Oklahoma and Georgia. Over two dozen states and seventeen large national parks across the country recognize it as a significant invasive plant of natural areas. It invades open habitats, preferring full sun and can tolerate nutrient poor soils and harsh dry conditions.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | U.S. National Park Service |
Source | http://www.nps.gov/plants/alien/pubs/midatlantic/cestm.htm |
Comments: Kartesz (1994) gives Centaurea maculosa auct. non Lam. as a synonym of C. biebersteinii. Hickman (1993) accepts the name C. maculosa Lam. and states that is noxious weed in disturbed places and native to Europe. Name C. bierbersteinii followed here, with C. maculosa as a synonym. Native to Europe, exotic in North America, according to Jepson Manual.