ANGIOSPERMS 



221 



be understood best by selecting for description some simple 

 flower that has all the floral members, as, for example, the 

 buttercup. 



In such a flower there are four distinct sets of members 

 (Fig. 207). The outermost set has the color and the form 

 of small leaves, each 

 member being called 

 a sepal, and the whole 

 set the calyx. The 

 next inner set is usu- 

 ally the showy one, 

 with members of rel- 

 atively large size, 

 delicate texture, and 

 bright color, each 

 member being called 

 a petal, and the whole 

 set the corolla. The 

 set just within the co- 

 rolla comprises the stamens, which produce the pollen. 

 The central set is made up of the carpels, which contain 

 the ovules that are to become seeds. 



The endless variations of these sepals, petals, stamens, 

 and carpels, make the differences among flowers, and it is 

 astonishing in how many ways the variations of four parts 

 can be combined. It will be impossible to describe even 

 the conspicuous variations and combinations, but certain 

 general tendencies may be pointed out. It is important 

 for the student to examine as many of the common flowers 

 of his neighborhood as possible, and to discover how they 

 differ from one another; for it is these floral differences 

 that are most used in classifying Angiosperms. 



132. Sepals. While the sepals generally look like small 

 green leaves, this is by no means always true. Sometimes 

 they are as brightly colored as petals; and often they appear 



FIG. 207. Flower of peony : k, sepals; c, petals; 

 a, stamens; g, carpels. After STRASBURGER. 



