PARTS OF THE FLOWER 



55 



40 to 44.) The calyx and corolla constitute the floral envelope 

 or perianth while the stamens and pistils are the sexual or essen- 

 tial organs of the plant. The arrangement of the organs in 

 circles permits the making of diagrams which represent the 

 general plan of a flower as clearly as a map shows the physical 



b 



Fio. 40. a, cherry blossom; b and c, diagrams showing the arrangement of the parts. 



Fia. 41. a, diagrammatic longitudinal section of apple blossom; b and c, peach blossom. 



and political divisions of the earth. If this diagram is accom- 

 panied by a second diagram made at right angles to the first, 

 the general architecture of the flower is well shown. 



The sepals and petals being leaf-like in character sometimes 

 grade imperceptibly the one into the other. In some flowers, of 

 which many lilies are examples, the parts of these outer circles 



