Bull Thistle

Cirsium vulgare

 

 

Description: This plant is a biennial forb. In the juvenile phase an individual can form a single rosette with a taproot up to 28 inches long. The rosettes can grow up to 3.3 feet in diameter.  The leaves of bull thistle are lance-shaped and anywhere from 3-12 inches long.  These leaves have prickly hairs on top and are very hairy on the underside.  Flowers are usually solitary and clustered near the ends of shoots and branches, measuring 1-2 inches long.  The fruits of bull thistle are achenes. 

 

Ecological Threat: This plant has no nutritional value for livestock and competes with desirable forage. The sharp spines of this thistle deter livestock and wildlife alike, truly making it a pest. 

 

Biology & Spread: Disturbed areas creative open habitats for seed production and seedling establishment of this invasive species. 

 

Threat in Oklahoma: This invasive species is not suitable for consumption by livestock or wildlife and inhibits the growth of native flora. 

Management:Integrated Management of Invasive Thistles in Oklahoma

Image Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org - See more at: http://www.invasive.org/browse/detail.cfm?imgnum=5162039#sthash.EeSCBIzR.dpuf

 

References:

Invasive Plant Atlas of the United States

Texas Invasives

Center for Aquatic and Invasive Plants

USDA PLANTS Database

Early Detection & Distribution Mapping System