EXPLANATION OF TERMS 



II 



with the petals united into a one-piece corolla, as in the Morning- 

 glory, Gilia, Pentstemon, etc. For purposes of convenience, 

 those exogens in which the petals are distinct are spoken of as 

 members of the Choripetalae, while those with united petals are 

 the Sympetalac. The former have also been known as "Poly- 

 petalae," the latter as "Monopetalae" and "Gamopetalae." Flowers 

 without a corolla are said to be apetalous. 



Filament 

 Stamen 



Receptacle 



A Pattern Flower. — The figure represents a choripetalous flower, with 

 sepals, petals, and stamens all distinct (not united) and inserted on the 

 receptacle. The single, simple pistil here figured has a superior ovary. 



The stamens supply the pollen used by the plant in fertilizing 

 the ovules, which then develop into seeds. This pollen is usually 

 produced in the form of a yellow powder contained in a 2-celled, 

 terminal pouch, the anther. At maturity the anther opens, scat- 

 tering the pollen, or it may be carried by insects or by the wind, 

 etc. The thread-like stalk of the stamen is the Ulament. 



The pistil always occupies the center of the flower and is con- 

 cerned with the bearing of seeds. It may be single, as in the 

 Poppy and Primrose, or there may be several or many pistils to 

 a single flower, as in the Buttercup. A complete pistil consists 

 of three parts: (1), the ovary, or enlarged base, which includes 

 one or more ovules, each of which is the forerunner of a seed; 

 (2), a style, which is a usually slender continuation of the ovary 

 and supports (3), the stigma, which is sometimes a mere point to 

 the style, sometimes a flattish disk, sometimes a narrow line, 

 sometimes a broad blade. 



The function of the stigma is to catch the pollen-grains and, through the 

 action of its secretions, cause them to send microscopic tubes through the 

 tissues of the pistil to the ovules. Certain contents of the pollen-grain then 



