THE PISTIL 63 



covered with an epidermis or skin. The pistils are also subject 

 to many modifications, but are always borne on the receptacle. 

 However, if the other organs originate below the ovary, it is 

 saici to be superior (as in the peach flower), but if they origin- 

 ate above it, it is said to be inferior (as in the apple blossom). 

 The arrangement of the organs in the flower can be described 

 by three terms: liypogynous (Fig. 44), the simplest form, 

 in which the sepals, petals, and stamens arise from below 



Fio. 50. Squash blossoms. A gamopetalous flower. 



X 



the carpels; perigynous (Fig. 40), in which the receptacle is 

 extended into a cup-like structure about the carpels and bearing 

 the sepals, petals and stamens on its rim and frequently more 

 or less united at their bases ; and epigynous, in which this cup 

 envelops the ovary, thus giving the true inferior ovary. 



The modified leaves of which the pistil is composed are 

 frequently called the carpels, and the point of attachment of 

 the ovules is called the placentae. The placentae may be either 

 central or parietal (i.e., on the sides of the ovary). The num- 

 ber of carpels can usually be determined by cutting a cross sec- 

 tion of the ovary and examining with a hand lens ; the number of 

 carpels being represented by the number of fibrous bundles 

 which correspond to the midribs of the leaves of which the 



