262 HOW CROPS GROW. 
other. If the rudimentary leaves of abud be represented 
by a nest of flower-pots, the smaller placed within the 
larger, the stem may be signified by a rope of India- 
rubber passed through the holes in the bottom of the 
pots. The growth of the stem may now be shown by stretch- 
ing the rope,whereby the pots are brought away from each 
other, and the whole combination is made to assume the char- 
acter of a fully developed stem, bearing its leaves at regular 
intervals; with these important differences, that the por- 
tions of stem nearest the root extend more rapidly than 
those above them, and the stem has within it the material 
and the mechanism for the continual formation of new 
buds, which unfold in successive order. 
In fig. 45, which represents the two terminal buds of a 
lilac twig, is shown not only the external appearance of 
the buds, which are covered with leaf-like scales, imbricated 
like shingles on a roof; but, in the section, are seen the 
edges of the undeveloped leaves attached to the conical 
axis, -All the leaves and the whole stem of a twig of one 
summer’s growth thus exist in the bud, in plan and in 
miniature. Subsequent growth is but the development 
of the plan. 
In the flower-bud the same structure is manifest, save 
that the rudimentary flowers and fruit are enclosed within 
the leaves, and may often be seen plainly on cutting the 
bud open. 
Culms; Nodes; Internodes.—The-grasses and the com- 
mon cereal grains have single, unbranched stems, termed 
culms in botanical language. The leaves of these plants 
clasp the stem entirely at their base, and at this point. is 
formed a well-defined, thickened knot or node in the stem. 
The portions of the stem between these nodes are termed 
internodes. 
Branching Stems,—Other agricultural plants besides 
those just mentioned, and all the trees of temperate cli- 
