bluebuttons, field scabious USDA PLANTS Symbol: KNAR
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Knautia arvensis (L.) Coult.
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Taxonomic Rank: Magnoliopsida: Dipsacales: Caprifoliaceae
Synonym(s): field scabiosa, field scabious
Appearance
Knautia arvensis is a tall hairy perennial herbaceous plant that grows to about 4 ft (1.3 m) tall. It has a long taproot and tends to form clumps. K. arvensis is native to Europe and temperate Asia. It was introduced for use as an ornamental and has escaped cultivation.
Foliage
The opposite leaves are quite variable. They can be simple or compound with margins entire or serrate.
Flowers
The lilac to purple flowers are held in a dense rounded inflorescence from 0.6-1.6 in (1.5-4 cm) wide. Individual flowers have four lobes, are funnel-shaped and are from 0.4-0.5 in (9-12 mm) long.
Fruit
One plant can produce up to 2000 seeds which may remain viable in the soil for many years. The fruit are four angled hairy achenes from 0.2-0.24 in (5-6 mm) long.
Ecological Threat
K. arvensis infestations establish easily along roadsides, in pastures, fields, meadows and fallow areas. The seeds have an eliosome, which is collected by ants as food, then carried back to their nest. This process aids in the plant's dispersal.
Selected Images from Invasive.orgView All Images at Invasive.org


Flower(s);
Steve Dewey, Utah State University, Bugwood.org
Additional Resolutions & Image Usage
EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org 		 


State List
This map identifies those states that list this species on their invasive species list or law.

Invasive Listing Sources:
Pacific Northwest Exotic Pest Plant Council, 1998