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Western Wetland Flora

Field Office Guide to Plant Species

Creeping Thistle
Cirsium arvense (L.) Scop.

JPG -- Species Photo JPG -- Distribution Map

Family: Composite (Compositae)
Flowering: June-August
Field Marks: This thistle can be distinguished usually by its small flower heads that are usually less than 1 inch long and 1/2 inch wide.
Habitat: Bottomland areas, ditches, old fields, disturbed areas.
Habit: Perennial herb from a thickened, deep rootstock.
Stems: Upright, branched, up to 4 feet tall, usually covered with white, cobwebby hairs.
Leaves: Alternate, simple, usually pinnately lobed, up to 6 inches long, up to 3 inches wide, smooth or white-hairy, the lobes bearing sharp spines; leaf stalk up to 1/2 inch long or absent.
Flowers: Many crowded together into a head, with several heads per plant; each head less than 1 inch long, less than 1/2 inch across, subtended by 5-6 rows of small spine-tipped, green bracts; flowers all tubular.
Sepals: 0.
Petals: 5, pink or purple, forming a tube up to 1 inch long.
Stamens: 5.
Pistils: Ovary inferior.
Fruits: Achenes pale brown, topped by a cluster of white or gray plumose bristles up to 1 inch long.
Notes: The female and male flowers are usually borne in separate heads on separate plants.

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U.S. Department of the Interior | U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/plants/florawe/species/8/cirsarve.htm
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Page Last Modified: Saturday, 02-Feb-2013 06:27:47 EST
Reston, VA [vaww55]