200 Science of Plant Life 



which bear the individual flowers in a flower cluster are called 

 pedicels. 



The parts of the flower. The apex of the flower stalk is 

 called the receptacle. It is often enlarged and serves as a 

 place of attachment of the various floral organs. The outer 

 whorl of scales or leaflike organs is the calyx. It usually is 

 green in color, and in the bud stage it completely incloses the 

 flower. The individual parts of the calyx are called sepals. 

 Next inside the calyx is a whorl of white or brightly colored 

 leaves that make up the corolla. The several parts of the 

 corolla are called petals. The corolla is usually the attractively 

 colored part of the flower ; but in some flowers, as in the tulip 

 and clematis, the sepals have the same coloring as the petals. 

 The calyx and corolla are often spoken of as the floral envelopes, 

 because in the bud they form a wrapping, or envelope, for 

 the inner parts of the flower. 



Inside the corolla is a group of stamens, each composed of 

 a stalklike filament and an anther that contains the pollen. 

 The center of the flower is occupied by one or more pistils, 

 each made up of an ovulary, style, and stigma. The ovulary 

 is the enlarged part of the pistil that contains the ovules, 

 which develop into the seeds. The style is the stalk above 

 the ovulary that bears at its summit the stigma. The stigma 

 is usually an enlarged surface, which secretes a sticky, sugary 

 solution in which the pollen grains are caught and germi- 

 nated. The pistils and stamens are called the " essential or- 

 gans " of the flower, because they produce the ovules and 

 pollen which are the two elements necessary for the production 

 of seed. 



The variety of floral structures. The above is a descrip- 

 tion of a typical flower; but in the plant world we find an 



