450 



THE ROSALES 



the flower Is strictly epigynous. In the rose family, which is 

 very closely connected w^ith the preceding group, this story of 

 change in the evolution of the flower is repeated. In the simpler 

 forms the mass growth of the receptacle and calyx, forms a cup- 

 like structure (perig^^nous flower). This cup may be rather 

 broad and shallow as in the strawberry, cinquefoil and black- 

 berry (Fig. 312), but in higher types the receptacle more or less 

 completely surrounds the pistils as in the spiraea, avens, rose, 

 agrimony (Fig. 313). In the apple family, including the apple, 



Fig. 312. Fig. 313. 



Fig. 312. A member of the rose family with the simple structure of the 

 saxifrages: A, flower of the strawberry (Fragaria). B, section of flower 

 showing slight adhesion of receptacle to calyx and the spiral arrangement of 

 the sporophylls. C, the fruit, akenes spirally arranged on the enlarged and 

 fleshy receptacle. 



Fig. 313. Higher forms of the rose family: C, flower of Agrimonia. D, 

 section of flower, showing the bristle-cove ed receptacle completely surround' 

 ing the pistils. 



peach, quince, shadbush, thornapple, hawthorn, the ovules are 

 completely enveloped by the receptacle (Fig. 314, A-C) as in 

 the currants, while in the plum family, with its plum, prune, 

 cherry, peach, almond, apricot members, the pistils are reduced 

 to one and are quite distinct from the cup-like receptacle (Fig. 



The senna family has essentially the same type of flower as 

 the plum save that the pistil usually contains many seeds (nor- 



