Cuaprer III. 
Leaves. 
LEAVES are the lungs of plants. The food taken in by 
the roots has to pass through the stem to the leaves to be 
acted upon by the air, before it becomes sap and is fit to 
be used for the growth of the plant. No portion of a 
plant is more varied in parts, forms, surface, and dura- 
tion than the leaf. 
No one can become familiar with leaves, and appreciate 
their beauty and variety, who does not study them upon 
the plants themselves. This chapter therefore will be 
devoted mainly to the words needed for leaf description, 
together with their application. 
THE Lear.—In the axil of the whole leaf the bud 
forms for the growth of a new branch. So by noting the 
position of the buds, all the parts included in a single leaf 
can be determined. As a general thing the leaf has but 
one blade, as in the Chestnut, Apple, Elm, ete.; yet the 
Horse-chestnut has 7 blades, the Common Locust often has 
21, and a single leaf of the Honey-locust occasionally has 
as many as 300. Figs. 17-58 (Chapter VIL.) are all illus- 
trations of single leaves, except Fig. 48, where there are 
two leaves on a twig. A number of them show the bud 
by which the fact is determined (Figs. 25, 26, 31, 33, 34, 36, 
40, ete.); others show branches which grew from the ax- 
illary buds, many cf them fruiting branches (Figs. 37, 42, 
43, 50, and 54), one (Fig. 51) a thorny branch. 
The cone-bearing plants (Figs. 59-67) have only sim- 
ple leaves. Each piece, no matter how small and scale- 
like, may have a branch growing from its axil, and so 
may form a whole leaf. A study of these figures, together 
D) 7 
