| Russian knapweed | U.S. Nativity: Exotic Habit: Forbs/Herbs |
| Rhaponticum repens (L.) Hidalgo |
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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae |
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| Synonym(s): hardheads | |
Russian knapweed is a perennial forb that can grow to 3 ft. (1 m) in height. Stems originate from a basal rosette of leaves. The rosette leaves can be unlobed to very lobed and are 2-4 in. (5-10 cm) long. Stem leaves are oblong, pinnately lobed to entire and up to 6 in. (15.2 cm) in length at the base of the stem and become smaller and less lobed toward the top. In summer to fall Russian knapweed produces flowers that are pink to purple and turn straw colored as they mature. The flower heads are approximately ½ in (1.2 cm) in diameter and urn shaped. Fruits (achenes) are ivory-colored with a tuft of hair that falls off at maturity. Russian knapweed is native to Eurasia and was introduced into the United States in the early 1900’s. This species can cause chewing disease in horses. |
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Identification, Biology, Control and Management Resources
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| Selected Images from Invasive.org | View All Images at Invasive.org |
 Seedling(s); Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Flower(s); Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Flower(s); Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Feature(s); Bud stage with detached bracts Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Norman E. Rees, USDA Agricultural Research Service - Retired, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Norman E. Rees, USDA Agricultural Research Service - Retired, Bugwood.org Additional Resolutions & Image Usage |
 Plant(s); Steve Dewey, Utah State University, Bugwood.org Additional Resolutions & Image Usage |
 Infestation; Norman E. Rees, USDA Agricultural Research Service - Retired, Bugwood.org Additional Resolutions & Image Usage |
 Fruit(s); Steve Hurst, USDA NRCS PLANTS Database, 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(s) Where Reported invasive. Based on state level agency and organization lists of invasive plants from WeedUS database. |
