32 INTERRELATIONS OF PLANTS AND ANIMALS 



The Essential Organs. — A flower, however, could have no 

 sepals or petals and still do the work for which it exists. The 

 essential organs of the flower are within the floral envelope. They 

 consist of the sta'mens and pis' til (or pistils), the latter being in the 



center of the flower. 

 The structures with the 

 knobbed ends are called 

 stamens. In a single 

 stamen the boxlike part 

 at the end is the anther; 

 the stalk which holds 

 the anther is called the 

 fiVament. The anther is 

 in reality a hollow box 

 which produces a large 

 number of little grains 

 called pollen. Each 

 pistil is composed of a 

 rather stout base called 

 the o'vary and a more 

 or less lengthened por- 

 tion rising from the 

 ovary called the style. 

 The upper end of the 

 style, which in most 

 cases is broadened, is 

 called the stigma. The 

 free end of the stigma 

 usually secretes a sweet 

 fluid in which grains of 

 pollen from flowers of 

 the same kind can grow. 

 Insects as Pollinating 

 Agents. — Insects often 

 visit flowers to obtain pollen as well as nectar. In so doing they 

 may transfer some of the poflen from one flower to another of the 

 same kind. This transfer of pollen, called cross-pollination, is of 

 the greatest use to the plant, as we shall see later. Sir John 



Ovule 



Cross sec f ion 

 of ovary 



A simple flower, seen from above {A) and in sec- 

 tion {B) ; and its separate parts. 



Sepdl Petal Stdmsn Mil 



