COMPOSITE FAMILY 



COMPOSITAE 



SPINY-LEAVED SOW THISTLE 



Sonchus asper (L.) Hill 



This plant is a native of Europe but it is widely distributed 

 in nearly all cultivated parts of the earth. Although it must be 

 classed as a weed, it is a very showy and beautiful one when 



the pale yellow flowers are in 

 bloom from May to late autumn. 

 Like many other members of 

 the Composite family this species 

 has flowers which open only when 

 the sun shines. 



It is an annual with fibrous 

 roots. The stem is i-io feet high 

 and not much branched. It is 

 leafy toward the base but much 

 less so toward the top. The leaves 

 usually have few lobes and some- 

 times none, but they are very 

 spiny toothed. The lower and 

 basal are petioled, whereas the 

 upper are clasping and with basal 

 earlike lobes. Stem and leaves con- 

 tain an abundance of milky juice. 



The blooming season is May 

 to late autumn. The heads are 

 several and often numerous. The 

 involucre is more or less bell shaped and usually becomes thick- 

 ened at the base and more or less cone shaped when old. The 

 bracts are smooth and arranged in several series, the outer ones 

 successively smaller. The receptacle is flat and naked. The 

 corollas are strap shaped and 5-toothed at the end. Each ot the 

 flat and margined akenes, 3-nerved on each side but otherwise 

 smooth, has a very abundant pappus of soft white bristles. 



The Common Sow Thistle, Sonchus oleraceus L., is very similar 

 to the spiny-leaved species, but the leaves are usually more lobed 

 and not spiny, and the akenes are longitudinally fine ribbed and 

 wrinkled crosswise. The plant is a common weed in most cultivated 

 parts of the world except the extreme north, and has been naturalized 

 in this country from Europe. 



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