THE PARTS OF A PLANT AND THEIR WORK 17 
LESSON IV 
Stems and leaves 
Materials——Some stems or branches from plants such as 
those studied in the first lesson, and some from trees and 
shrubs. One specimen from each should be cut and put in a 
warm place for a day before the lesson, and one from each 
should be fresh. Leaves, when present, should be left upon 
all specimens. A young sunflower plant, a coleus, and a 
begonia, which have been allowed to dry until they are con- 
siderably wilted. A day before this lesson place in alcohol 
leaves from a number of plants—beech, maple, bean, corn, 
etc.; also have some fresh leaves in the laboratory. 
If a considerable number of specimens are available, this 
lesson should be made into two. 
The stem.—Compare the fresh and the wilted speci- 
men of each kind of plant at hand as to the ease with which 
they bend or break; as to their ability to support their leaves 
in an upright position. How do the branches from the 
shrubs and trees differ from the others? To what is the 
difference due? Place a number of the wilted stems in 
water and see whether they regain their former position. 
Note and sketch the position of the stem and leaves of the 
wilted plants. 
Pour water into the pots in which the plants are grow- 
ing, and approximate the time required for the leaves and 
stem to assume a normal position. Can you see any of the 
leaves move as they regain their position? 
The leaf—Remove the leaves from the alcohol and 
note their color and that of the alcohol. The alcohol has 
removed the green coloring-matter—chlorophyll—from the 
leaves. 
Select a compound leaf, such as that of the maple or 
bean, and study carefully its system of veining. Is the main 
axis of the system one midrib or several parallel veins? 
