slenderflower thistle USDA PLANTS Symbol: CATE2
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Carduus tenuiflorus W. Curtis

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): Italian thistle, winged plumeless thistle
Native Range: Africa & Europe (GRIN);

Slenderflower thistle is an herbaceous winter annual or biennial that invades disturbed areas. The most serious infestations occur in the Pacific coastal states, but slenderflower thistle also occurs sporadically in the eastern United States. Plants grow up to 6 ft. (1.8 m) tall with single or multiple spiny stems with wings arising from the base of the spines. Stem wings can be up to 0.4 in. (10 mm) wide. Leaves are deeply lobed and also very spiny. The small flower heads (less than 1 in. [2.5 cm] long) are slender, purple, and lack stalks. Flowering occurs from May to July. Slenderflower thistle invades pastures, old fields, vacant lots, and other disturbed areas. Its presence reduces the forage productivity of pastures. Slenderflower thistle is native to Europe and was recognized as a serious invader in the western United States as early as 1956.

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org


Plant(s); in flower. From Weeds of California and other Western States.
Evelyn Healy, University of California - Davis, Bugwood.org
Additional Resolutions & Image Usage

Plant(s); un-attacked rosette free from crown weevil
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
Additional Resolutions & Image Usage

Infestation;
Eric Coombs, Oregon Department of Agriculture, Bugwood.org
Additional Resolutions & Image Usage

Feature(s); flowering stems. From Weeds of California and other Western States.
Joseph M. DiTomaso, University of California - Davis, 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.

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