920 A TEXTBOOK OF GENERAL BOTANY 
resemble single flowers (Figs. 224, 225), as is the case with . 
the sunflower, cosmos, daisy, and chrysanthemum. 

Fig. 224. Single flower (x 12) 
and flower head (x 2) of a sun- 
flower (Helianthus cucumerifolius) 
In the single flower the parts from 
below upward are ovary, calyx, 
corolla, stamens, and stigma 
flowers frequently have odors, 
although in many cases they 
are odorless. The odors are 
due to essential oils which are 
volatile and odoriferous. 
The essential oils of lowers 
are extensively employed in 
the manufacture of perfumes, 
toilet waters, and face and 
Odors of flowers. Many flow 
ers possess odors which serve to 
attract insects, and a large num- 
ber of inconspicuous flowers are 
pollinated by insects that are at- 
tracted by the odor. Conspicuous 

Fig. 225. Single flower (x 2) and flower 
head (x 3) of marigold 
In the single flower the expanded por- 
tion is the corolla; in the center of this 
are shown the style and the stigma sur- 
rounded by stamens 
sachet powders. Various methods such as steam distillation, extrac- 
tion with fats (preparation of flower pomades),and extraction with 
volatile solvents are used to obtain the perfume oils from flowers. 

