ORGANS OF VEGETATION 



143 



Stamen. 



a, Filament; 

 b, anther. 



find the next set of organs called the pistils. The pistils and sta- 

 mens taken together are called the essential organs, since their 

 presence is necessary for the production of the seed of the 

 plant. 



A stamen consists of the filament or stalk, and the anther, 

 which is the essential part. The anther contains a fine dust- 

 like substance called pollen, which fertilizes the flower 

 and makes it productive. The dustlike particles of 

 pollen when examined under a microscope are found 

 to be of various forms and shapes. 



The pistil, when only one is present, occupies the 

 center of the flower; when there are two pistils, they 

 stand facing each other; but when there are several, 

 they commonly form a ring or circle. The pistil when 

 complete has three parts: the ovary, style, and stigma. 

 The ovary is the rounded portion at the base, which is 

 hollow and contains one or more ovules or rudimentary seeds. 

 The style is a slender, tapering stem borne by the ovary. The 

 stigma is found at the end of the style and it has a naked, moist 

 surface upon which grains of pollen lodge and 

 fertilize the ovules in order that they may become 

 seeds. 



Some plants, such as the pear and the tomato, 

 have blossoms which contain both stamens and 

 pistils in the same flower, while others, like Indian 

 corn, bear their stamens and pistils in separate 

 flowers. Sometimes both staminate and pistillate 

 flowers are on the same plant, but frequently 

 they are on entirely separate plants. In the 

 hemp plant and the hop vine the staminate 

 flowers grow on one plant and the pistillate flowers on another. 

 Flowers having both pistils and stamens are called perfect 

 flowers, while those having only one of these organs are known as 

 imperfect flowers. 



Pollination. When the stigma has been supplied with pollen, 

 a threadlike or tubelike growth is sent down through the pistil 

 to the ovules and they become seeds. This process when com- 

 pleted constitutes what is known as fertilization. 



stigma 



style 



ovary 



Pistil. 



