FORM AND STRUCTURE 
The roots of the deciduous trees of North America are 
usually a modified form of the tap root, often a divided tap 
soot with fibrous rootlets. 
STEM. 
The stem is that part of the plant axis which bears the 
leaves, flowers and fruit, and is the means of communication 
between them and the root. The stem differs from the root 
not only in that it is leaf-bearing but its branches are ar- 
ranged regularly and the growing point is at the apex of the 
branches. A stem increases in length by the growth of a 
terminal bud and its branches normally originate from buds, 
The points on the stem where the leaves appear are called 
nodes. 
‘The parts of the stem between the nodes are called inter- 
nodes, 
‘The angle formed by the upper side of a leaf and the stem 
is called the axil. 
LEAVES. 
Leaves are stem-appendages and consist of expansions of 
the stem tissues. J oliage leaves are usually flat, bi-laterally 
symmetrical organs, green in color, and 
presenting a distinct upper and under 
surface. They are pre-eminently the 
assimilating organs of the plant; out 
of the crude sap under the influence of 
light and air they elaborate the plant 
food, 
A Typical Leaf consists of three 
parts, the blade, the petiole, and the 
stipules; any one of these parts may 
be wanting. (Fig. 3.) 
The Blade is the expanded portion of 
the leaf and the part to which the word 
leaf is usually applied. The Petiole is 
the leaf stalk. The Stipules are small 
leaf-like bodies, borne at the base of the petiole, usually 
one on each side. These are often united. Frequently 
507 
Fic. 3.—A Typical Leaf. 
