COMPOSITE FAMILY 



COMPOSITAE 



ENTIRE-LEAVED ROSINWEED 



Silphium integrifolium Michx. 



The Entire-leaved Rosinweed is common on prairies from 

 Ohio to Minnesota and south to Louisiana and Texas. The 

 abundant resinous juices of this and related species are often 



used by children for chewing 



gum. 



The plant is perennial and 

 has a stout stem that is 

 sometimes smooth and some- 

 times rough hairy. It grows 

 2-5 feet high and branches 

 near the top. The leaves, us- 

 ually entire but sometimes 

 slightly toothed, are opposite, 

 and because they are thick 

 and rigid the plant is also 

 called Stiff Rosinweed. Their 

 form is ovate to ovate-lanceo- 

 late, and they are rough 

 above and hairy or smooth 

 beneath. Those of the stem 

 are closely sessile and often 

 half-clasping by the rounded 

 ^ base. 



The heads of yellow flowers are quite numerous in August and 

 September. The ray flowers are 15-25, pistillate and akene bear- 

 ing. All but the inner bracts of the involucre are broad and have 

 spreading leaflike tips. The receptacle is flat and chaffy. The 

 akenes are flat oval or obovate, broadly winged and deeply 

 notched at the top. There is no pappus. 



The Cup Plant, Silphium perfoliatum L., grows in low moist 

 places. The stem is square, stout and smooth and 4-8 feet high. The 

 leaves are opposite, ovate and coarsely toothed, and the larger are 

 6-12 inches long and 4-8 inches wide. The upper leaves are grown 

 together by their bases, forming cup-shaped receptacles which are 

 often partly filled with water and drowned insects. The heads are 

 quite numerous and 2-3 inches broad. The 20-30 ray flowers are about 

 I inch long. The akenes are winged and sometimes 2-toothed. 



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