Spotted knapweed
| Spotted knapweed | |
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Cynareae |
| Genus: | Centaurea |
| Species: | C. maculosa |
| Binomial name | |
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Centaurea maculosa Lam. |
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| Synonyms | |
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Centaurea beibersteinii (lapsus) |
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Centaurea beibersteinii (lapsus)
Centaurea biebersteinii (Jaub. et Spach) Walp.
Centaurea maculosa is a species of flowering plant in the family Asteraceae.
Centaurea maculosa, the spotted knapweed, is a species of Centaurea native to eastern Europe. This short-lived perennial usually has a stout taproot, pubescent stems with wooly or cobwebby hairs when young. The erect or ascending plant stems grow 20 to 150 cm tall. It grows on stream banks, pond shorelines, sand prairies, old fields and pastures, roadsides, and along railroads, and many open, disturbed areas. Apparently, is should be treated with two varieties as (Centaurea stoebe var. stoebe and var. micranthos (S.G. Gmel. ex Gugler) Hayek.
It has been introduced to North America, where it is considered an invasive plant species in much of the western United States and Canada. In 2000, C. maculosa occupied more than 7 million acres (28,000 km2) in the US.
Knapweed is a pioneer species found in recently disturbed sites or openings. Once it has been established at a disturbed site, it continues to spread into the surrounding habitat. This species outcompetes natives through at least three methods:
Its seed is an achene about a quarter of an inch long, with a small bristly pappus at the tip which makes the wind its primary means of dispersal. The leaves are a pale grayish-green. They are covered in fine short hairs. First year plants produce a basal rosette, alternate, up to 6 inches (150 mm) long, deeply divided into lobes. It produces a stem in its second year of growth. Stem leaves are progressively less lobed, getting smaller toward the top. The stem is erect or ascending, slender, hairy and branching, and can grow up to three feet tall. Because cattle prefer the native bunchgrass over knapweed, overgrazing occurs, increasing the density and range of knapweed infestations. Human disturbance is also a major cause of infestations. Knapweed readily establishes itself and quickly expands in all growth forms in places of human disturbance such as industrial sites, along roadsides, and along sandy riverbanks, and also has the potential to spread into undisturbed natural areas.
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Wikipedia