34 —. “BLEMENTARY BOTANY 
CHAPTER VI 
THE FLOWER 

eae IF the flower of a buttercup is examined, it will be 
a Modified seen to consist of four sets of leaves, arranged on — 
Shoot. a central stem; this stem is the apex of the s 
stalk, and is called the as The leaf, in the angle of | 
which the flower stalk 
is situated, is a bract ; 
it is not always pre- 
sent. A flower is thus 
a modified shoot, differ- 
ing from the ordinary 
foliage shoot already 
described as having : 

1, Very short inter- 
nodes. 
2. No buds in the axils. 
Fig. 84.—VERTICAL SECTION OF BUTTERCUP. 3. Leaves frequently 
re, receptacle ; s, sepals; p, petals; a, whorled and _ specially 
stamens ; ¢, carpels. 3 modified for the produc- 
tion of seed. 
Floral The outermost leaves of the flower are called 
Leaves. ‘sepals, and together form the calyz or cup, in 
which the rest of the flower is, as it were, contained. This is 
best seen in the bud where, as in poppy, the calyx forms a 
complete covering for the other floral leaves and, as soon as 
the flower opens, drops off * 
The next leaves are the petals, forming the corolla. The 
calyx and corolla are not essential for the development of 
fruit and seed, and are often absent, especially in the flowers 
of trees. 
The essential leaves of a flower are: (1) the stamens, the 
third whorl of leaves, and (2) the carpels, the innermost leaves. 

