THE FLOWER 



83 



sists of a calyx, composed of sepals; a corolla, composed of petals; 

 the stamens and one or more pistils established on a shortened 

 stem known as the torus or receptacle. 



The calyx is composed of one or more circies of leaf-like 

 organs, which form the outer covering for the flower bud and 

 the outer part of the open flower. Each part is known as a 

 sepal. The sepals are usually green, but in some cases are bright- 

 colored and can be readily mistaken for petals. They may be 



FIG. 63. The parts of the flower; (a) pistil, (6) stamen, (c) petal, (d) sepal, (e) receptacle. 



separate and distinct or united into a collar-like structure. They 

 are modified leaves which serve primarily for the protection of 

 the other parts of the flower. 



The corolla is composed of pne or more circles of expanded 

 structures just within the circle of sepals. Each part is known 

 as a petal. The petals are also specialized leaves and may be 

 leaf-like in form or very much modified. Thev are usually 

 bright-colored and may be separate or united. 



The calyx and corolla constitute the floral envelope or peri- 



