494 



ANGIOSPERMS 



The family includes a number of ornamental plants, of which 

 the Cornflower (also called Bachelor's Button), Marguerite, China 

 Aster, Chrysanthemum, Cosmos, Dahlia, and English Daisy are 

 familiar ones. 



In number of weeds which it includes this family surpasses all 

 others. About one hundred plants of this family are classed 



Fig. 446. — The Marguer- 

 ite, one of the Composites, 

 showing the flowers grouped 

 into a compact head and sur- 

 rounded by an involucre. In 

 this composite a head con- 

 tains two kinds of flowers — 

 ligulate flowers, one of which 

 is shown at the left, and tu- 

 bular flowers, one of which is 

 shown at the right of the 

 heads. After Lecomte. 



Fig. 447. — Canada 

 Thistle, showing a horizontal 

 root and an aerial stem in 

 flower (X|), and also show- 

 ing single fruits or achenes, 

 one of which is shown with- 

 out pappus and slightly en- 

 larged. 



as weeds, although not many of them are bad weeds. The 

 Canada Thistle (Fig. 447) is probably the worst weed of the 

 family. It spreads rapidly by spreading roots or rootstocks 

 and soon takes possession of pastures and meadows and gives 

 considerable trouble in cultivated ground. On account of the 

 spreading underground structures which propagate readily when 

 cut into pieces, the plant is exceedingly hard to eradicate. Some 

 of the other Thistles are also quite troublesome in some regions. 



