DEVELOPMENT OF PLANTS 



417 



m an interesting series of departures from the simple type noted 

 above that lead in very regular gradations to the highest forms 

 of the order. In the higher family of the saxifrages, for example, 

 which includes the saxifrage, false miterwort (Tiarclla), heu- 

 chera, bishop's cap (Mitella), golden saxifrage (Chrysosplenium), 

 the receptacle adheres to the ovary (Fig. 311, A, B) so that the 

 flower is, in a measure, epigynous and the carpels are reduced 



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. C, the fruit, akenes spirally 

 arranged on the enlarged and fleshy receptacle. 



Fig. 313. Higher forms of the rose family: A, flower of the rose. B, 

 section of flower, showing the cup-like receptacle surrounding the pistils. 

 C, flower of Agrimonia. D, section of flower, showing the bristle-covered 

 receptacle completely surrounding the pistils. 



to two and partly fused. Passing to the families of the hy- 

 drangeas, syringas (Philadelphus), currants (Ribcs) , etc., the 

 receptacle and carpels are quite fused (Fig. 311, C, D) and 

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

 very closely connected with the preceding group, this story of 

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

 forms the receptacle adheres to the calyx, forming a cup-like 

 28 



