he same
thing, and have no likeness to the _nerves_ and little to the veins of
animals.

129. _Netted-veined_ leaves belong to plants which have a pair of
seed-leaves or cotyledons, such as the Maple (Fig. 20, 24), Beech (Fig.
33), and the like; while _parallel-veined_ or _nerved_ leaves belong to
plants with one cotyledon or true seed-leaf; such as the Iris (Fig. 59),
and Indian Corn (Fig. 70). So that a mere glance at the leaves generally
tells what the structure of the embryo is, and refers the plant to one
or the other of these two grand classes,--which is a great convenience.
For when plants differ from each other in some one important respect,
they usually differ correspondingly in other respects also.

[Illustration: Fig. 113. A (parallel-veined) leaf of the Lily of the
Valley. 114. One of the Calla Lily.]

130. Parallel-veined leaves are of two sorts,--one kind, and the
commonest, having the ribs or nerves all running from the base to the
point of the leaf, as in the examples already given; while in another
kind they run from a midrib to the margin, as in the common
Pickerel-weed of our ponds, in the Banana, in Calla (Fig. 114), and many
similar plants of warm climates.

131. Netted-veined leaves are also of two sorts, as in the examples
already referred to. In one case the veins all rise from a single rib
(the midrib), as in Fig. 112, 116-127. Such leaves are called
_Feather-veined_ or _Penni-veined_, i. e. _Pinnately-veined_; both terms
meaning the same thing, namely, that the veins are arranged on the sides
of the rib like the plume of a feather on each side of the shaft.

132. In the other case (as in Fig. 74, 129-132), the veins branch off
from three, five, seven, or nine ribs, which spread from the top of the
leaf-stalk, and run through the blade like the toes of a web-footed
bird. Hence these are said to be _Palmately_ or _Digitately_ veined, or
(since the ribs diverge like rays from a centre) _Radiate-veined_.

133. Since the general outline of leaves accords with the framework or
skeleton, it is plain that _feather-veined_ (or _penni-veined_) leaves
will incline to elongated shapes, or at least to be longer than broad;
while in _radiate-veined_ leaves more rounded forms are to be expected.
A glance at the following figures shows this.

[Illustration: Fig. 115-120. A series of shapes of feather-veined
leaves.]

134. =Forms of Leaves as to General Outline.= It is necessary to give
names to the p