IV. FLOWER 



A flower of Sedum, from the side; 

 ^, anther of stamen; C, carpel; 

 F, filament; P, petal; S, sepal. 



Structure of a Simple Flower. — For the following exercise, the 

 buttercup and Sedum (stonecrop) are good. They may be ob- 

 tained in the fall.^ 



The expanded portion of the flower stalk, 



which holds the parts of the flower, is called 



the receptacle. The green leaflike parts cover- 

 ing the unopened flower are called the sepals. 



Sometimes the sepals are all joined or united 



in one piece. Taken together, they are caUed 



the calyx. Notice that the sepals come out 



in a circle or whorl on the flower stalk. How 



many sepals do you find ? In what respect 



do they resemble leaves? Are there any 



evidences as to their use or function ? 



The more brightly colored structures are the 



petals. Taken together, they form the co- 

 rolla. The corolla is of importance, as we 



shall see later, to make the flower conspicuous. 

 Compare the petals and sepals In this 



flower. Are sepals and petals in any respects 



like leaves ? 



A flower, however, could live without 



sepals or petals and still do the work for 



which it exists. The essential organs of the flower are within the so-called 



floral envelope. They consist of the stamens 

 and carpels (or pistils). The latter are in the 

 center of the flower. The structures with 

 the knobbed ends are called stamens. How 

 many stamens do you find, and what is 

 their position ? 



In a single stamen the boxlike part at the 

 end is the anther; the stalk is called the fila- 

 ment. The anther is in reality a hollow box 

 in which a dustlike material called pollen is 

 produced. It is necessary for the life of the 

 plant that the pollen get out of the anther. 

 Try to find how it gets out. 



Pistil. — Each carpel or pistil is composed 

 of a rather stout base called the ovary, and a 

 more or less lengthened portion rising from 

 the ovary called the style. The upper end 

 of the style, which in some cases is somewhat 

 broadened, is called the stigma. The stig- 



matic surface usually secretes a sweet fluid in which grains of pollen from 



flowers of the same kind can grow. 



* See Hunter and Valentine, Manual, page 54. 



31 



A flower of Sedum from above; 

 A, anther; C, carpel; F, fila- 

 ment; P, petal; S, sepal. 



