CHAPTER LI 

 SOME FAMILIES OF FLOWERING PLANTS 



The flowering plants are very numerous both in species and in indi- 

 viduals, extremely variable in structure, and of great economic impor- 

 tance. It is not possible in one chapter to discuss more than a few of 

 the 300 families that compose this great assemblage of plants. The few 

 that are discussed here are selected on the basis of their abundance, 

 economic value, or some other feature that makes them of peculiar 

 interest (Fig. 330). 



Fig. 330. The large-leaved magnolia in flower and in fruit. Photo by R. B. Gordon. 



The grass family (Gramineae or Poaceae). The progress of man from 

 the dawn of civilization to the present has been dependent upon the 

 grasses more than upon other groups of plants. The fact that primitive 

 man changed from a nomad to a settler was due in large measure to 

 his discovery that the seeds and fruits of grasses, along with those of 

 some other plants, could be obtained in greater amounts bv means of 

 cultivation and after harvest be stored for his use at some future time. 

 Even the calendar mav have been suggested bv the necessit\' of know- 

 ing recurring periods connected with cereal agriculture: time of plant- 

 ing, of cultivating, of ripening, and of harvesting. 



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