ROSACEA. 55 



It is especially difficult in the Rose family, 

 which includes plants of very variable struc- 

 tures. Some orders or families are more 

 natural than others ; they include plants 

 which agree in possessing some one or more 

 peculiar distinguishing characters. Exam- 

 ples of such families are the Cruciferse or 

 Mustard family, Umbelliferae or Parsnip 

 family, and Compositae or Sunflower family. 

 The Rose family is not so well defined as 

 many other families. As now understood it 

 includes two or 

 thiee families 

 recognized by 

 the older bota- 

 nists. We shall 

 find it profita- 

 able to examine 

 a few rosaceous 



Fig. 45. 



flowers before considering the general defini- 

 tion of the order. Fig. 45 represents a cherry 

 flower cut in two lengthwise. At j) is seen 

 the pistil, the lower part of which (the 

 ovary) ripens into the cherry. At c c is 

 shown the calyx, upon the top of which are 

 borne the stamens and the petals. The end 

 of the flower-stalk where it joins the flower, 

 /•, is called the receptacle. Fig. 46 represents 



