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HILL^S THISTLE 



Cirsiutn hillii (Canby) Fern. 



Summer Grotesque and somewhat over-elaborate as a flower. 



Roadsides, prairies Hill's thistle in June sets its large flowers above 



ten-to-twenty-inch stalks on the sunshiny prairie. 

 The plant is low and stout and finely downy, as well as extremely prickly 

 on the twisted and deeply cut and spiny leaves. It always appears as if 

 this thistle plant were buried in the gTound with only the last half foot 

 or so thrusting through the tough prairie sod. But this is a characteristic 

 of the Hill's thistle and the closely related bull thistle. 



The flower of Hill's thistle is a large, globular head of bright rose- 

 purple or pink, or rarely white, florets bursting from the prickly, orderly 

 receptacle with its individual line prickles standing out at intei"vals. The 

 flower is a composite mass of long purple florets from which thrust the 

 powdery, cream-white stamens and the long, thin pistils. When the thistle 

 is fertilized, usually by butterflies, the flower becomes a mass of downy 

 fluff, at the base of which are the seeds. Wlien goldfinches come to eat 

 the seeds and use the silk for nest-building purposes, the released silks 

 often float away on tlic wind. 



The low, compact Hill's thistle is found on open prairie land along 

 tlie highways and occasionally in prairie pasture land. The very large 

 flowers are instantly noticed even by passing motorists, and by botanists 

 seeking typical plants of the Illinois ])rairie. 



The common bull thistle (Cirsium vulgare) is a biennial plant, three 

 to five feet tall, which has come to us from Europe and has become estab- 

 lished in pastures and old fields througbout the state. Its leaves are green 

 on both sides, which serves to distinguish it from the field thistle, which 

 has leaves white beneath. 



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