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 ee 
set the corolla. ‘The "9: 207-—Flower of peony: t, spa «petal 
set just within the co- 
rolla comprises the Soren 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 
