54 FLOWERING PLANTS 

Fig, 22.—STEM oF DrApD- 
NETTLE, CORTEX  RE- 
MOVED. (Diagrammatic. ) 
n, node - bearing leaves; 
im, internode; c, central 
bundle ; 7, lateral bundles ; 
w, wing bundles. 
tinuous with each other. 
the central bundle (c) of each leat- 
bearing side of the stem passes 
down through two internodes. This 
central bundle is the median bundle 
of the leaf. At the node where 
there is no leaf on its side of the 
_ stem it simply joins by short trans- 
verse trunks the bundles on each 
side of it; but when the second 
node, that bearing a leaf, is reached, 
the bundle forks and its branches 
fuse with the same two lateral 
bundles. Two other bundles, called 
wing bundles (w), are seen at the 
node, one on each side of the 
lateral leaf-bundle. A transverse — 
section of the petiole of the leaf 
shows also five bundles, one central, 
two lateral, two wing (Fig. 23). 
It is also clear from Fig. 22, that 
the single corner bundle in Fig. 20 
consists of two lateral bundles, 
one from each side of the stem. It 
will be seen from what has just 
been said that in the Dead-nettle 
the bundles are common to stem 
and leaf. In some cases, however, 
the bundles of the stem do not 
terminate in the young leaves, but 
in the growing point of the stem ; 
these bundles are said to be cauline, 
because they belong to the stem 
alone. As a rule the bundles of 
Dicotyledons run _ longitudinally 
and parallel to each other. It 
need hardly be said that the bundles 
of root, stem, and leaf are con- 

