COMPOSITAE 



COMPOSITE FAMILY 



PRICKLY LETTUCE. MILK THISTLE 



Lactuca Scariola L. 



The Prickly Lettuce seems to have been introduced into this 

 country from Europe about 1863 and is now common nearly 

 throughout. In some places the young leaves are collected in 

 great quantities in spring and used 

 as a salad vegetable. Sheep eat the 

 young leaves quite greedily and 

 cattle seem to like them also. Gen- 

 erally, however, it is considered a 

 noxious weed because its hard stems 

 dull reaping knives and its copious 

 juice is a major annoyance in thresh- 

 ing machinery. 



The stem is stiff, leafy and branch- 

 ed near the top. It grows 2-7 feet 

 high and is smooth, except that the 

 lower portion is somewhat prickly. 

 The alternate leaves are spiny 

 toothed, sessile and clasping, and 

 usually there is a row of prickles 

 along the whitish green midrib below. 



The heads are very numerous 

 with 6-12 pale yellow flowers, bloom- 

 ing from July to September, in each. 

 The involucre is cylindrical and the 

 outer bracts are only about a third 

 as long as the inner. The brown 

 akene has a threadlike beak of 

 equal length, and a white pappus of 

 silky hair. 



The Wild Lettuce or Horseweed, Lactuca canadensis L., grows 

 3-10 feet high and is smooth throughout. The leaves are quite 

 variable. Those of the main stem are usually somewhat pinnately 

 lobed, sessile or clasping, and 2-8 inches long. The upper ones are 

 usually smaller and entire, and sometimes all are nearly white. 

 Each of the numerous heads contains 12-20 pale yellow flowers. 

 The akenes are oval, flat and about as long as the slender beak. The 

 pappus is white. Moist open places are favored by this plant, from 

 Nova Scotia to British Columbia and south to Georgia, Alabama, 

 Arkansas and Colorado. 



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