70 INTRODUCTION TO BOTANY 
leaves with the veins running somewhat parallel to each other. 
Sometimes, as in the canna (fig. 50), the veins run both ways 
from a midrib, but oftener, as in corn and the other grasses, 
the veins run from the base to the tip of the leaf. This latter 
system of veining is most commonly found in long, narrow 
leaves. Most dicotyledons have net-veined leaves. These 
are of two types: those like the leaf of the willow, oak, and 
Fia. 50. Parallel-veined 
leaf of canna, veins Ame 
running from midrib Fic. 51. An apple twig in the autumn 
to margin Alternate arrangement of leaves 
peach, with the smaller veins running both ways from a mid- 
rib; and those like the geranium, hollyhock, and cucumber, 
with the veins radiating from the base of the leaf, like the 
sticks of a fan (fig. 49). Net-veined leaves with feather- 
like veining frequently have a length several times as great as 
their width, while those with fan-like veining are often round- 
ish in their general outline. Whatever the shape of the leaf, 
the veining is so disposed that a ready means of distribution 
throughout the leaf is offered to the water brought into it through 
