STEMS 51 
64. Twig of Poplar.— Sketch a vigorous young twig of poplar (or 
of hickory, magnolia, tulip tree) in its winter condition, noting par- 
ticularly the respects in which it differs from the horse-chestnut. 
Describe in writing any facts not shown in the sketch. Notice that 
the buds are not opposite, nor is the next one above any given bud 
found directly above it, but part way round the stem from the 
position of the first one. Ascertain, by studying several twigs and 
counting around, which bud is above the first and how many turns 
round the stem are made in passing from the first to the one directly 
above it. 
Observe with especial care the difference between the poplar and 
the horse-chestuut in mode of branching, as shown in a large branch 
provided for the study of this feature. 
65. Relation of Leaf Arrangement to Branching.! — This 
difference depends on the fact that the leaves of the horse- 
chestnut were arranged in pairs on opposite sides of the 
stem, while those of the poplar were not in pairs. Since 
the buds are found at the upper edges of the leaf-scars, and 
since most of the buds of the horse-chestnut and the poplar 
are leaf-buds and destined to form branches, the mode of 
branching and ultimately the form of the tree must depend 
largely on the arrangement of leaves along the stem. 
66. Opposite Branching. — In trees, the leaves and buds 
of which are opposite, the tendency will be to form twigs 
in four rows about at right angles to each other along the 
sides of the branch, as shown in Fig. 24. 
This arrangement will not usually be perfectly carried 
out, since some, of the buds may never grow, or some may 
1 The teacher in the Eastern and Middle States will do well to make con- 
stant use, in the study of branches and buds, of Newell’s Outlines of Lessons 
in Botany, Part I. The student can observe for himself, with a little guid- 
ance from the teacher, most of the points which Miss Newell suggests. If the 
supply of material is abundant, the twigs employed in the lessons above 
described need not be used further, but if material is scanty, the study of buds 
may at once be taken up. (See also Bailey’s Lessons with Plants, Part I.) 
