Rosinweed      Silphium integrifolium


Description: The Rosinweed is a native, warm-season perennial belonging to the Composite, or aster family. It reaches a height up to nearly two meters. It has a dense, fibrous root system.

 

Leaf: Its rather small, rough, pointed leaves are opposite on the stem and attached directly to the stem. They measure from 7 to 15 cm long and 2.5 to 5 cm wide. The leaves are so rough that they cannot be easily rubbed.

 

Flower: The yellow heads are up to 5 cm. broad. They are composed of both disk and ray flowers. The rays are about 0.5 cm. long and number up to 25.

 

Blooming months: July – September

 

 

 

 

8-20

8-20

10-13

 

Discussion: It is named for its resinous sap. Native Americans and settlers chewed its gummy sap to clean their teeth.

 

Distribution: This species is common in the prairies of Illinois. Rosinweed ranges from Wisconsin south to Alabama and Kansas.

 

Native or Introduced to Illinois: Native

 

Location: N41048.677’ W089040.972’

 

Copyright: © 2004 Nancy Trainor, Challand Middle School, Sterling, Illinois

                                ntrainor@sterlingschools.org

References:

Keller, Carolyn. Prairie Plants of Whiteside County, Whiteside IL County Natural Area Guardians, 1991.

Ladd, Doug. Tallgrass Prairie Wildflowers, The Nature Conservancy, 1995.

Peterson, Roger Tory. Wildflowers Northeastern/North Central North America, Houghton Mifflin Company, Boston, 1968.

Mohlenbroch, Robert H., and John W. Voigt. Prairie Plants of Illinois, Department of Conservation.

http://plants.usda.gov/

 

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