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Species
Centaurea stoebe subsp. micranthos (Gugler) Hayek 1931
IUCN
NCBI
EOL Text
- Plant: herbaceous biennial or perennial plant.
- Leaves: a basal rosette of deeply lobed leaves is produced the first year; rosette leaves are deeply lobed, stalked and about 8 in. long; stem leaves are alternate and may be slightly lobed or linear; leaves become smaller and less lobed toward the apex.
- Flowers, fruits and seeds: flowering stems are 2/3- 4 ft. tall and branched; flowers are produced early summer after the first year and resemble tiny pineapples topped with a showy ring of pink to light purple, highly dissected petals; the bract tips of the base (“pineapple”) are dark, giving the spotted look for which the plant is named.
- Spreads: by wind-dispersed seed.
- Look-alikes: other knapweeds and thistles including Canada thistle (Cirsium arvense) which occurs in similar habitats in the mid-Atlantic region.
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 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 |
Spotted knapweed is found at elevations up to and over 10,000 feet and in precipitation zones receiving 8 to 80 inches of rain annually. Spotted knapweed prefers well-drained, light-textured soils that receive summer rainfall, including open forests dominated by ponderosa pine and Douglas fir, and prairie habitats dominated by Idaho fescue, bluebunch wheatgrass, and needle-and-thread grass. Disturbance allows for rapid establishment and spread; however, spotted knapweed is capable of invading well managed rangelands. Spotted knapweed does not compete well with vigorously growing grass in moist areas. In seasonally dry areas, spotted knapweed's taproot allows it to access water from deep in the soil, beyond the reach of more shallowly rooted species.
Centaurea biebersteinii (Spotted Knapweed)
(also known as Centaurea maculosa; the butterfly sucks nectar, while beetle activity is unspecified; information is limited; observations are from Herms, MacRae, and Swengel & Swengel)
Butterflies
Lycaenidae: Lycaeides melissa samuelis fq (Hm, Sw)
Beetles
Buprestidae: Acmaeodera tubulus (McR)
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2002-2015 by Dr. John Hilty |
Source | http://www.illinoiswildflowers.info/flower_insects//plants/sp_knapweed.htm |
The nectar of the flowers attracts various long-tongued bees, butterflies, and skippers. Various insects from abroad have been introduced to control this species (and other Knapweeds), including Cyphocleonus achates (Knapweed Root Weevil), Agapeta zoegana (Yellow-Winged Knapweed Moth), Sphenoptera jugoslavica (Yugoslavian Root Beetle), and two Urophora spp. (Seedhead Flies). It is possible that some granivorous birds and small rodents eat the seeds to a limited extent. Mammalian herbivores normally shun this plant because of the bitter foliage; but they will eat it if little else is available, as occasionally occurs in overgrazed pastures. Some of the seeds of Spotted Knapweed can pass through the digestive tracts of livestock and remain viable; thus, these animals may help to distribute the seeds. People also help to spread Spotted Knapweed by means of their motor vehicles (the seedheads can become caught on the under-carriage) and through the transportation of baled hay or contaminated seed stock.
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 plants in North America generally live 3 to 7 years but can live up to nine years or longer. Plants regrow from buds on the root crown. Reproduction is by seed, and plants are capable of producing 500- 4,000 seeds per square foot per year. About 90% of the seeds are viable at the time of dispersal, and they can remain viable in the soil for 5-8 years. Most seeds are dispersed near the parent plant but can be transported by people, wildlife, livestock, vehicles, and in soil, crop seed, and contaminated hay. Gravel pits, soil stockpiles, powerlines, grain elevators, railroad and equipment yards are important seed distribution points.
Spotted knapweed was introduced to North America from Eurasia as a contaminant in alfalfa and possibly clover seed, and through discarded soil used as ship ballast. It was first recorded in Victoria, British Columbia in 1883 and spread further in domestic alfalfa seeds and hay before it was recognized as a serious problem.
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
Spotted knapweed was accidentally introduced into North America in the late 1800s in contaminated alfalfa and clover seed and in soil used for ship ballast. In North America, plants generally live 3 to 7 years but can live up to nine years or longer and regrow from buds on the root crown. Reproduction is by seed. Individual plants are capable of producing an estimated 500-4,000 seeds per square foot per year. Most of the seed is viable at the time of dispersal and can remain viable in the soil for 5-8 years. Most seed is dispersed near the parent plant but can be moved great distances by people, livestock, wildlife, and vehicles and in soil, crop seed, and contaminated hay.
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 |