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Wavy-Leaf Thistle

Wavy-Leaf Thistle
Cirsium undulatum (Nutt.) Spring.
(Order Asterales; Family Asteraceae)
 


Wavy-Leaf Thistle and sulfur butterfly (Kansas Wildflowers and Grasses: http://www.kswildflower.org/flower_details.php?flowerID=58)


Diagnosis:
Stems: The stems are simple or sparingly branches. They are grooved, erect, and stout. They are leafy as well. They can grow anywhere from 1 to 4 feet high.
Leaves: The leaves are alternate, crowded and usually pinnately lobed. Their shape is laceolate to elliptic and range from 4 to 12 inches long and 1 to 3 inches wide. They are light green on the top side and densely white-woolly below. The margins are wavy and bear yellow spines.
Inflorescence: The inflorescence is one, solitary urn-shaped head at the terminal end of the plant. It ranges from 1 to 1.5 inches wide. There are bracts that are conspicuous light-colored ridges on the back and they are tipped with short spines.
Flowers: Unlike most Asteraceae flowers, the ray florets are absent. The disc florets are numerous in number and are purple to pink.
Fruits: The fruits are called achenes and are smooth and brown. They are tipped with white feather-like bristles and enclosed a small seed.


Flowering Period: This flower blooms in June, July and August.


Distribution: Cirsium undulatum in the United States. From the USDA Plants Database http://plants.usda.gov/java/profile?symbol=CIUN

 

Distribution Kansas: From the USDA Plants Database http://plants.usda.gov/java/profile?symbol=CIUN

 

Native Status: Wavy-Leaf Thistle is native to both the United States and Kansas.


Habitat: These plants are predominately found in dry prairies, over-grazed pastures, roadsides, and open disturbed areas.


Uses: The Native Americans used the roots as a food source and to make a medicinal tea.  
 

Conservation status: Secure

 

Links: 
Kansas Wildflowers & Grasses: http://www.kswildflower.org/flower_details.php?flowerID=58

References:
Weberling, Focko , & Pankhurst, R.J. (1992). Morphology of flowers and inflorescence. Great Britain: University Press, Cambridge.

 

Image Credits:
Kansas Wildflowers and Grasses: http://www.kswildflower.org/flower_details.php?flowerID=58

United States and Kansas Distribution Map from the USDA Plants Database http://plants.usda.gov/java/profile?symbol=CIUN

 

Submitted by: Kiersten Dixon, July 2011.

 

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