Appearance

Centaurea calcitrapa is a biennial to perennial plant. It grows 2-3 ft. (0.61-0.91 m) tall.

Foliage

The stems and leaves are covered with fine hairs. Lower and basal leaves are divided or deeply lobed. Leaves become less divided toward the apex of the plant.

Flowers

Flowering occurs from July to October when purple to pink blooms develop at the ends of the stems. Floral bracts are tipped with 1 in. (2.5 cm) long, straw-colored spines.

Fruit

The fruit is an achene 0.08-0.16 in. (2-4 mm) long which lacks a pappus.

Ecological Threat

A native of southern Europe, Centaurea calcitrapa produces prolific seeds and often invades floodplains, dry forests, and grasslands.

Citations

Winston, R.L., Andreas, J.E., Milan, J., DesCamp, W., Randell, C.B., and M. Schwarzlander. 2014. New Invaders of the Southwest. United States Department of Agriculture, Forest Health Technology Enterprise Team. FHTET-2014-12. Retrieved from https://bugwoodcloud.org/resource/files/14767.pdf

Winston, R.L., Andreas, J.E., Milan, J., DesCamp, W., Randell, C.B., and M. Schwarzländer. 2014. New Invaders of the Northwest. United States Department of Agriculture, Forest Health Technology Enterprise Team. FHTET-2014-12. Retrieved from https://www.fs.fed.us/foresthealth/technology/pdfs/FHTET-2014-12_NW_New_Invaders.pdf
 

Selected Images

Maps

Invasive Listing Sources

• Arizona Noxious Weeds
• California Invasive Plant Council
• California Noxious Weeds
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Nevada EDRR
• Nevada Noxious Weeds
• New Invaders of the Northwest
• New Invaders of the Southwest
• New Mexico Noxious Weeds
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Utah Noxious Weeds - Early Detection
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States

References