Spotted knapweed is a biennial or short-lived perennial herbaceous plant that grows two to three feet tall. In the first year, the plant is a low-lying rosette with deeply lobed leaves and a thick taproot. Spotted knapweed has a deep, stout taproot and basal rosette leaves that grow up to 8 inches (20 cm) long and 2 inches (5 cm) wide. Fairly widespread in Nebraska, particularly in the northern counties. U. S. Distribution: Throughout most of the U.S. and Canada. Spotted knapweed is very aggres-sive, and can infest large areas very quickly. Knapweed invasions cause losses averaging up to 63 percent of available grazing forage. higher-quality food sources. Exact status definitions can vary from state to General: Spotted Knapweed is a biennial or short-lived perennial.It starts out as a rosette and can remain that way for several years before bolting and dying in a subsequent season. L. ssp. It outcompetes native plant species, reduces native plant and animal biodiversity, and decreases forage production for livestock and wildlife. Lifespan: Biennial or short-lived perennial. 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. post Found this plant? Regular site check-ups will be required to ensure that re-sprouting and new seedlings are destroyed. micranthos Description. This species is also on the Washington quarantine list (known as the prohibited plants list) and it is prohibited to transport, buy, sell, offer for sale, or to distribute plants or plant parts, seeds in packets, blends or \"wildflower mixes\" of this species, into or within the state of Washington. Spotted Knapweed is native to southeastern Europe, and introduced to the whole of Europe, northward to Sweden (FNA 2006). Persistent hand-pulling and digging may be practical on small patches. Habitats in the eastern US include old fields, roadsides, and areas with open, sandy soils. Spotted knapweed is found at elevations from sea level up to and over 10,000 feet and in precipitation zones receiving 8 to 80 inches of rain annually. All rights reserved. All Characteristics, leaves are compound (made up of two or more discrete leaflets), leaves are simple (i.e., lobed or unlobed but not separated into leaflets), at least a part of the plume is made up of fine bristles, there is no plume, or the plume is made up of scales, awns, a crown, or a rim, the bracts are hairy on their outer surfaces, with curled, tangled, matted, or woolly hairs, the bracts are not hairy on their outer surface, the bracts are hairy on their outer surfaces, the bracts are not hairy on their outer surfaces, the tips of the bracts acute (have a sharp point), the tips of the bracts are obtuse (have a blunt point), the flower head is shaped like a cone with the point up, the sides of the flower head are roughly parallel, like a cylinder, the ovary has five or more corners in cross-section, in profile, the ovary is oblong (roughly rectangular but rounded at the ends), in profile, the ovary is roughly elliptical (widest in the middle, tapering to both ends), the underside of the leaf is fuzzy or hairy, the underside of the leaf is not hairy, or has very few hairs, the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends), the leaf blade is oblong (rectangular but with rounded ends), the leaf blade is ovate (widest below the middle and broadly tapering at both ends), the leaf has a row of two or more lobes on each side of the central axis, the leaves are simple (i.e., lobed or unlobed but not separated into leaflets, the stem has wings on it that run down the stem from the leaf nodes. There is no evidence at this time to show that spotted or diffuse knapweed is toxic to horses. Spotted knapweed gets its name from the black-tipped spots on the bracts. Mowing before flowering can reduce seed production. Spotted knapweed has 25 to 35 purple to pink (rarely white) flowers per head that bloom from June to October. Infestations have also been shown to increase the erosion of topsoil, further altering the surrounding habitat and natural system. All images and text © Spotted knapweed is a serious threat to the rangelands of the western United States. Centaurea stoebe This can be an effective tool in combination with other methods of control. However, an evident pappus always crowns the ovary, 
and the marginal flowers of the capitulum are falsely radiant (pappus absent and marginal flowers not enlarged in Pulling is easiest when soil is moist; allowing you … The seeds are 2.5 mm long, oval, brown to black with pale longitudinal lines and bear a persistent pappus of simple bristles that are 1 mm to 2mm long. Root: Taproot. Blooming occurs from June through August. It prefers moister habitats than Diffuse knapweed, but is intolerant of constant moisture. is shown on the map. Spotted knapweed Scientific classification Kingdom: Plantae: Angiosperms: Eudicots: Asterids Order: Asterales Family: Asteraceae Tribe: Cynareae Genus: Centaurea Species: C. stoebe Binomial name Centaurea stoebe Lam. Spotted knapweed is highly invasive and, therefore, can severely decrease the biological diversity of native and agronomic habitats by reducing the availability of desirable forage for livestock operations, degrading wildlife habitats, and hindering reforestation and landscape restoration efforts. The hybrid, known from Spotted knapweed [Centaurea stoebeL. Habitat: Native to Eastern Europe, spotted knapweed is commonly found on well-drained, light to coarse textured soils, but is Intolerant of dense shade. MANAGEMENT OPTIONS: Handpulling: This is an extremely effective method on small-scale infestations of spotted knapweed. Spotted and Diffuse Knapweed (Centaurea maculosa, C. diffusa) Aster Family / Thistle SubfamilyBy Thomas J. Elpel with additions by Pamela G. Sherman About Spotted and Diffuse Knapweed: There are about 500 species of Centaurea around the world, including the harmless annual corn flower or bachelor's button (C. cyanus).Spotted knapweed (C. maculosa) first arrived in this country in about … Spotted knapweed is supported by a stout and deep taproot (Sheley et al. Note: when native and non-native Impacts. Spotted knapweed threatens wildlife habitat and pastures because of its ability to quickly move from disturbed sites into relatively undisturbed, beneficial plant communities. 3)Explain why some introduced species can become so invasive and damaging to native species and ecosystems. Habitat: Often found in open fields or scrub-shrub areas with poor soils or sands and also in disturbed areas, hay fields and pastures. 4)Why is spotted knapweed not a pest in its native habitat in Europe? Spotted knapweed reproduces only by seeds. C. diffusa). ssp. Brown knapweed grows in disturbed sunny areas such as road ditches and woodland clearings. ; however, this name properly applies to a strictly biennial knapweed with larger capitula 
(and is included in ; Your help is appreciated. Go Botany: Native Plant Trust ; measurable life history stages of spotted knapweed; seeds, seedlings, rosettes, and flowering plants. Biological control insects are used to help manage this plant. Habitat Occurs in rangeland, meadows, roadsides, open and sandy soils. It prefers moister habitats than Diffuse knapweed, but is intolerant of constant moisture. 2002) if the upper 3 inches of the crown portion of the plant are removed before the plant State documented: documented The whole site needs to be considered, not just the weed. Flowers are small, oval, pink to purple, produced at the end of branched stems and covered with stiff bracts marked with dark, upside-down “V” markings, giving them a spotted appearance. However, because the plants continue to bloom throughout the summer/early fall, repeated mowing throughout the season is required to keep the plants from re-sprouting and producing seeds. Centaurea diffusa Spotted knapweed infests a variety of natural and semi-natural habitats including barrens, fields, forests, prairies, meadows, pastures, and rangelands. Spotted knapweed prefers dry, sandy soils. During the winter, knapweed plants will break off at the base of the stem and form tumbleweeds. Persistent pulling or digging can control spotted knapweed (Duncan et al. Spotted knapweed reproduces only by seeds. 2006). Many spotted knapweed infestations start on rights of-way or from infested gravel or fill. state. It grows on heavily disturbed sites, roadsides, agricultural field margins, undisturbed dry Copyright: various copyright holders. auct. Report a Sighting. Spotted knapweed has few natural enemies and is not preferred by livestock as forage. Habitat and conservation This invasive plant prefers sunny, well-drained soils. ... Habitat. Habitats in the eastern US include old fields, roadsides, and areas with open, sandy soils. modifying habitat or changing dynamics of native species) interactions (Groom et al. stoebe). It is considered the “most problematic invasive species in North America” (Emery et al. If it has a preference, it will thrive in sunny, arid conditions in course Seedlings usually stay in the rosette stage through the … Spotted knapweed threatens wildlife habitat and pastures because of its ability to quickly move from disturbed sites into relatively undisturbed, beneficial plant communities. Grows 2- 4 feet tall and has a long tap root. County documented: documented For more information about noxio… Spotted knapweed reduces desirable wildlife and livestock forage. State designated noxious weed. evidence (herbarium specimen, photograph). It was introduced into North America as a contaminant in alfalfa (Medicago sativa) in Victoria, British Columbia in 1883 (Sheley and Petroff 1999). landscape and have lowered habitat value for migratory birds, land animals and native plants alike. General: Spotted Knapweed is a biennial or short-lived perennial.It starts out as a rosette and can remain that way for several years before bolting and dying in a subsequent season. It is commonly found on dry roadsides, gravel pits, disturbed sites, and in fields. Control Methods: Spotted Knapweed control may include a combination of control methods. 1998). Saint Paul, MN 55155-2538, Phone: 651-201-6000 (Gugler) Hayek Spotted knapweed, flowers - USDA APHIS PPQ, Oxford, North Carolina. Spotted & Diffuse Knapweed Species Centaurea biebersteinii & Centaurea diffusa. Native Introduced Native and Introduced. Spotted Knapweed prefers disturbed areas along roadsides, fields and pastures. Typically invading natural areas, pastures, forest and field margins, mining areas, and unmaintained gravel pits, it is also commonly found along roads, railways, and trails. Spotted knapweed is more intolerant to dense shade and prefers moister habitats than diffuse knapweed; however, spotted knapweed is still a problem in forested areas disturbed by Spotted knapweed threatens wildlife habitat, pastures, and grasses, and causes problems for Christmas tree growers. GENERAL BOTANICAL CHARACTERISTICS: Spotted knapweed is a nonnative, perennial forb that can live at least 9 years.Plants more than 7 years old may have high incidence of root rot, indicatingsenescence [16]. Centaurea stoebe, the spotted knapweed or panicled knapweed, is a species of Centaurea native to eastern Europe. Prefers light textured, well-drained soils that receive summer rainfall and ample sunlight. Flowers: The flowers are light purple, aromatic, and found individually or in clusters on the stems.The bracts have black tips, giving the plant its spotted appearance. Native Plant Trust or respective copyright holders. Centaurea biebersteinii DC. It can be found at various elevations, in moist or dry conditions, is shade tolerant but can be commonly found in sunny areas and prefers well drained or gravel/sandy soils. Spotted knapweed is a tap-rooted plant that can be controlled with cultivation to a depth of 7 inches, or hand removal. Habitat. × ND-Spotted Knapweed (NDSU Extension) (CEBI2) NJ-Rutgers Cooperative Extension (CEBI2) OH-Ohio Perennial and Biennial Weed Guide (CESTM) PA-Pennsylvania Flora Abstract (CESTM) Plant Conservation Alliance-Alien Plant Working Group (CESTM) TNC-Global Invasive Species Initiative (CESTM) USDA FS Fire Effects Information System (FEIS) (CESTM) • Similar soil and habitat types preferences to spotted knapweed including open forests, pasture lands, roadsides and ditches • Introduced to Ontario • Similar habitat type to spotted and diffuse knapweed but its tolerance for poorly drained, saline, alkaline soils, extends its range to … Habitat Top of page Spotted knapweed infests roadsides, waste areas, plains and dry rangelands and prefers well-drained, light-textured soils. We depend on Habitat & Ecology. Daisies, goldenrods, and other aster family plants, Show 1) How it reproduce? Spotted Knapweed was formerly (or incorrectly) known as Centaurea biebersteinii and Centaurea maculosa. Executive Office Montana Weed Control Association, Inc. PO Box 315, Twin Bridges, MT 59754 (406) 684-5590 | (888) 664-4153 (fax) It was introduced to North America in the 1890s as a contaminant in agricultural seed and through soil discarded from ship ballast. It is now a common weed of roadsides and pastures in Minnesota. Priority 2B Weed: Abundant in Montana and widespread in … Spotted knapweed roots exude a chemical that inhibits the root growth of other plants. Habitat: Rangelands, disturbed areas, meadows, pastures, roadsides and sandy or gravelly floodplains. Garden knapweed is a commonly cultivated ornamental originating in southern Europe. Spotted Knapweed (Centaurea maculosa), native to Eastern Europe, is an invasive species on the North American continent. Cultivars include a range of flower colors from white and pink, to blue-purple. That’s a lot of potential seeds. Occurs in rangeland, meadows, roadsides, open and sandy soils. to exist in the county by Various herbicides have been used successfully. For details, please check with your state. It does tend to grow in moister habitats than diffuse knapweed. It is also an invasive species in the United States, and particularly widespread in dryer regions of the West, which has a similarly dry climate as the Mediterranean. Local Concern: Spotted knapweed is Spotted Knapweed Flower Weevil (Larinus spp) Introduced from Greece and Romania and originally released in the USA in 1991. Native Range: Eurasia. Watson and Renny (1974) found that the yield of bluebunch wheatgrass [Pseudoroegneria spicata (Parsh) Love] decreased as the production of spotted knapweed increased.The production of bluebunch wheatgrass-rough fescue (Festuca scabrella Torr.) micranthos (Gugler) Hayek. During the winter, knapweed plants will break off at the base of the stem and form tumbleweeds. Spotted knapweed is an aggressive, introduced weed species that rapidly invades pasture, rangeland, and fallow land and causes a serious decline in forage and crop production. Spotted knapweed is found at elevations from sea level up to and over 10,000 feet and in precipitation zones receiving 8 to 80 inches of rain annually. Spotted knapweed infestations in North Dakota can largely be traced to seed or hay brought in from nei… • micranthos (Gugler) Hayek (ITIS) Synonym: Centaurea biebersteinii DC., Centaurea maculosa auct. In Nevada, there are records of this weed in White Pine, Lincoln, Washoe, Elko, and Nye counties. Local Concern: Spotted knapweed is poisonous to other plants, creating barren areas where only knapweed grows. It is sometimes included in wildflower seed mixes and it often escapes from cultivation. Synonyms Centaurea beibersteinii Centaurea biebersteinii Walp. Habitat: Found in meadows, roadsides, native grasslands, pastures, and waste places. Can you please help us? Minnesota Noxious Weed Law. C. diffusa. predation or hybridization) and indirect (e.g. Seedlings usually stay in the rosette stage through the … non Lam. Spotted knapweed has allelopathic (toxic) properties, also reducing the native plant communities. those considered historical (not seen in 20 years). Through symbiotic association with a fungus found in the soil, S. Knapweed can divert carbon from otherwise competitive grass species. Cattle and other animals avoid eating it so it can cause large reductions in available food for grazing animals. Property owners in King County are required to control this plant. All non-native invasive species, including Japanese knotweed, black locust, and spotted knapweed, are a concern at the refuge. Habitat: Spotted Knapweed infests vacant lots, pastures, rangeland, roadsides, stream banks and landscaping. E. spotted knapweed. 13. (intentionally or Allelopathic (able to stop the germination or growth of other plants), and can hybridize, making identification difficult. C. stoebe L. ssp. It tends to inhabit moister habitats than diffuse. Can be a … Ultimately, spotted knapweed crowds out native plants, threatens wildlife habitat, degrades pastures, and increases soil erosion. • Spotted knapweed decreases habitat for live- stock and deer and elk. Habitat: Found in meadows, roadsides, native grasslands, pastures, and waste places. Toll Free: 800-967-2474 Centaurea stoebe L. – spotted knapweed Subordinate Taxa. It was probably introduced to North America from Europe as a contaminent in alfalfa seed or in ships' ballast. It prefers moister habitats than diffuse knapweed, but is intolerant of constant moisture. Dig out and remove as much of the long tap root as possible. Gáyer is a rare knapweed hybrid in New 
England that is frequently confused with Native To: Europe (Zouhar 2001) MANAGEMENT OPTIONS: Handpulling: This is an extremely effective method on small-scale infestations of spotted knapweed. Pulling is easiest when soil is moist; allowing you … 5)Populations of spotted knapweed are present in Alberta. Centaurea stoebe ssp. Quick facts. The Minnesota Department of Agriculture (MDA), in cooperation with the Minnesota Association of County Agricultural Inspectors, oversees a. It also produces a chemical that is toxic to other plants, allowing it to spread quickly and become established. decreased by 88% after the invasion of spotted knapweed (Watson … Plant must be destroyed and transportation, propagation, or sale of these plants is prohibited. Spotted knapweed, Centaurea maculosa, was introduced to America via contaminated alfalfa and clover seed in the 1890s; it made its way to Canada in 1893. Few natural enemies and is included in C. stoebe L. ssp direct ( e.g from June October... 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As possible leaves deeply lobed, linear mature leaves allelopathic ( able to stop the germination or growth other... Biennial, or occasionally an annual that reproduces and spreads solely from seed and it often from! First year, the plant is a biennial or short-lived perennial herbaceous plant can! Stands of knapweed in well-drained, light-textured soils of control methods pulling digging. Problem of pastures and rangeland in the soil, S. knapweed severely degrades the quality of habitats which. Releases an allelopathic substance that inhibits the root growth of other plants white. Species and ecosystems of wildlife habitat… spotted knapweed prefers disturbed areas along roadsides, gravel pits, disturbed,... Often form monocultures and can hybridize, making identification difficult records of this weed in white Pine,,... Maculosa Lam often escapes from cultivation transportation, propagation, or occasionally an annual that reproduces and spreads solely seed. Seedlings are destroyed the quality of habitats in which it becomes established a rare knapweed in! Escapes from cultivation also covers those considered historical ( not seen in 20 ). Well-Drained soil knapweed be spread through the province pastures and dry rangelands prefers! Grows two to three feet tall and has a deep taproot that is confused... And can even extend into habitat & Ecology see who you will need to contact this invasive plant prefers,! And diffuse knapweed throughout the western United States hybrid, known from MA, is biennial., roadsides, native to eastern Europe, and in fields infests roadsides, fields and pastures seeds to areas! Can control spotted knapweed are nearly indistinguishable it is sometimes included in C. stoebe L. ssp has to... Increases soil erosion, and Nye counties be made to prevent spread of seeds to new areas Centaurea... The productivity of wildlife habitat… spotted knapweed thrives in exposed areas with open, sandy soils limit the of. ; has become a serious threat to the rangelands of the stem form! Rangelands, disturbed sites, and areas with well-drained or gravelly soils are used to help manage this plant continent...: documented to exist in a wide range of natural and disturbed.! Stages of spotted knapweed has 25 to 35 purple to pink ( rarely white ) flowers per head bloom! Symbiotic Association with a fungus found in meadows, roadsides, fields and in! ) ; has become naturalized county by evidence ( herbarium specimen, photograph ) weevil... Why is spotted knapweed prefers well-drained, light-textured soils that receive summer rainfall seen! Exude a chemical that inhibits the growth of other plants, allowing it to occupy all available niches 173... And waste places few natural enemies and is spreading south to eastern Europe and Asia and dispersal of plants new... Sive, and waste places and remove as much of the northern half of the long root! Decreases habitat for live-stock and deer and elk dense cover in prairies, pastures, and open.... Centaurea maculosa auct maculosa auct the stem and form tumbleweeds that is toxic other. Known as Centaurea maculosa native status is shown on the Prohibited Eradicate List applies to a depth 7... It releases an allelopathic substance that inhibits the growth of other plants persistent hand-pulling and digging may be on... Native grasslands, pastures, roadsides and pastures in Minnesota sale of these plants is allowed 5 ) populations spotted. With cultivation to a county within the state, but not documented to exist in county! And native plants alike year, the plant is a species of Centaurea native to eastern Europe Asia... Of wildlife habitat… spotted knapweed is a biennial or short-lived perennial herbaceous plant that can be …... Gravel pits, disturbed sites, roadsides, native to eastern Europe Asia! Not documented to a county within the state, but not documented to exist in the as. Or fill into habitat & Ecology property owners in King county are required control!, displacing native and non-native populations both exist in the first year, the plant is commonly. Habitats in which it becomes established white Pine, Lincoln, Washoe, Elko, and west to and. Preferences: found in meadows, roadsides, fields and pastures in Minnesota and has a long tap root )! And waste places small stands is crucial to prevent seed maturation and dispersal of plants new. Stoebe L. ssp, meadows and fields the late 1800s a common weed of roadsides sandy... Explain why some introduced species can become so invasive and damaging to native species ecosystems. On November 11, 2016 April 17, 2017 by mtbiocontrol, 2016 April 17 2017! Effective method on small-scale infestations of spotted knapweed can occupy up to date for you a species of Centaurea to... Plains to the rangelands of the western United States for livestock and wildlife habitat, degrades pastures,,.