Russian knapweed

Russian knapweed

Taxobox
name = Russian Knapweed


image_width = 250px
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Asterales
familia = Asteraceae
tribus = Cynareae
genus = "Acroptilon"
species = "A. repens"
binomial = "Acroptilon repens"
binomial_authority = (L.) DC. (1837)
synonyms = "Centaurea repens"

Russian Knapweed ("Acroptilon repens") is a bushy rhizomatous perennial, up to 8 dm tall. Stems and leaves are finely arachnoid-tomentose becoming glabrous and green with age. The rosette leaves are oblanceolate, pinnately lobed to entire, 2-3 cm wide by 3-8 cm long. The lower cauline leaves are smaller, pinnately lobed; the upper leaves become much reduced, sessile, serrate to entire. The heads are numerous terminating the branches. Flowers are pink to purplish, the marginal ones not enlarged. The outer and middle involucral bracts are broad, striate, smooth with broadly rounded tips; the inner bracts are narrower with hairy tips. Pappus present with bristles 6-11 mm long. Fruit is a whitish, slightly ridged achene.

Russian Knapweed is a deep-rooted long lived perennial. Some stands have been in existence for 75 years. It forms dense colonies in cultivated fields, orchards, pastures, and roadsides.

A native to Eurasia, Russian Knapweed was introduced into North America in the late 1800s. Absent only from southeastern U.S., it has become widespread in other regions, especially in the western United States. [cite web | title = Acroptilon repens | url = http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200023016 | work = Flora of North America]

Russian Knapweed is the sole member of the monotypic genus "Acroptilon". The genus name derives from "acro-" (high) and "ptilo-" (feather). Although some sources include this species in the genus "Centaurea", molecular phylogeny results, the structure of the flower, and the chromosome number support recognizing it as a separate genus. [cite web | url = http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=100387 | title = Acroptilon | work = Flora of North America]

References

External links

* [http://plants.usda.gov/java/profile?symbol=ACRE3 USDA Plants Profile - With Many Links to Resources]
* [http://www.invasivespecies.gov/profiles/russknwd.shtml#fed U.S. Invasive species guide]
* [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?609,621,622 Jepson Manual Treatment]
* [http://tncweeds.ucdavis.edu/esadocs/acrorepe.html Photo gallery]


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • russian knapweed — noun Usage: usually capitalized R : a Eurasian herb (Centaurea picris) introduced into the central United States where it has become a troublesome weed …   Useful english dictionary

  • Acroptilon repens — ID 1158 Symbol Key ACRE3 Common Name hardheads Family Asteraceae Category Dicot Division Magnoliophyta US Nativity Introduced to U.S. US/NA Plant Yes State Distribution AR, AZ, CA, CO, IA, ID, IL, IN, KS, KY, MI, MN, MO, MT, ND, NE, NM, NV, OH,… …   USDA Plant Characteristics

  • List of plants by common name (Sonoran Desert) — This is a List of plants by common name (Sonoran Desert), for the Sonoran Desert and local environs; (S California, etc New Mexico, S, SW or Rio Grande Valley Northern Mexico states: Sonora, Chihuahua and Baja California, North and South, and… …   Wikipedia

  • List of invasive species — This is a list of invasive species by country or region. A species is regarded as invasive if it has been introduced by human action to a location, area, or region where it did not previously occur naturally (i.e., is not native), becomes capable …   Wikipedia

  • List of Asteraceae genera — This is a list of genera in the plant family Asteraceae, the daisies and sunflowers.A* Aaronsohnia Warb. Eig * Abrotanella Cass. * Acamptopappus (A.Gray) A.Gray goldenhead * Acanthocephalus Kar. Kir. * Acanthocladium F.Muell. * Acanthodesmos… …   Wikipedia

  • Liste D'espèces Invasives — Fleurs pourpres de Echium plantagineum, une plante extrêmement invasive qui infeste le Warrumbungle National Park en Nouvelle Galles du Sud ( Australie). L introduction, volontaire ou non, de nouvelles espèces dans un milieu peut entraîner des… …   Wikipédia en Français

  • Liste d'especes invasives — Liste d espèces invasives Fleurs pourpres de Echium plantagineum, une plante extrêmement invasive qui infeste le Warrumbungle National Park en Nouvelle Galles du Sud ( Australie). L introduction, volontaire ou non, de nouvelles espèces dans un… …   Wikipédia en Français

  • Liste d'espèces invasives — Fleurs pourpres de Ech …   Wikipédia en Français

  • Liste des espèces invasives — Liste d espèces invasives Fleurs pourpres de Echium plantagineum, une plante extrêmement invasive qui infeste le Warrumbungle National Park en Nouvelle Galles du Sud ( Australie). L introduction, volontaire ou non, de nouvelles espèces dans un… …   Wikipédia en Français

  • List of Canadian plants by genus — Below is a list of Canadian plants by genus. Due to the vastness of Canada s biodiversity, this page is divided.Many of the plants seen in Canada are introduced, either intentionally or accidentally. N indicated native and X indicated exotic.… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”