120 
THE FIRST BOOK OF BOTANY. 
EXERCISE XXXVIII. 
Essential Organs and Protecting Organs . 
The chief purpose of the flower is the production 
of seed; hut, to this end, some of its parts are more 
necessary than others: for example, the action of 
both stamens and pistil is needed in the formation of 
seeds, while they are often produced without the pres¬ 
ence of either calyx or corolla. The stamens and pis¬ 
til are therefore called the essential organs of flowers; 
and, as the calyx and corolla cover and nourish these, 
they have been called the protecting organs . 
Point out upon the charts the protecting organs 
of flowers. Point out the essential organs. Do you 
find both sets in all the flowers represented ? 
Examine your collection of flowers, and point out 
in each specimen the essential organs and the protect¬ 
ing organs. 
EXERCISE XXXIX. 
JDichlamyd'eous 9 Monochlamyd'eous, and Achla- 
myd'eous Flowers . 
When the protecting organs, calyx and corolla, 
are present in a flower, it is said to be diehlamydeous 
(Fig. 207). 
When there is but one whorl of protecting organs, 
whatever its color or texture, it is called a calyx , and 
the flower is monochlamydeous (Figs. 208 and 209). 
A flower destitute of protecting organs is achla< 
mydeous (Fig. 210). 
Achlamydeous flowers are said to be naTced . 
