FOLIAGE AND SCALE LEAVES. 57 
tions exist. In the sunflower, for example, there is a well- 
marked midrib, but the pair of lateral veins next the base are 
much stronger than the remainder. Exceptional dicotyledons 
are known in which the venation is more or less parallel. The 
wild plantains (Plantago) illustrate this. In them a number of 
strong veins take a curved course from base to apex, having 
between them, however, a typical network formed by small 
veins. 
The general shape or form of the lamina is correlated with the 
venation. Monocotyledons have generally leaves with simple 
outlines, which are longest when basal-veined. In dicotyledons 
long and short forms are associated respectively with pinnate 
and palmate venation. Details will be given below. 
It may be noted, as a general rule, that the most complicated 
outlines occur in small herbs, especially when these occur in 
crowded situations. The largest leaves are also, in many cases, 
found nearest the ground. The leaves of the same plant are 
by no means uniform either in shape or size. This is especially 
noticeable in herbs. ‘Take, for example, a tall buttercup plant. 
The lowest, so-called radical leaves, are here the largest and most 
complicated. They gradually pass into smaller and less compli- 
cated upper leaves. Much greater uniformity is found among 
the leaves of trees. 
It is not possible to make any exact classification of the in- 
numerable kinds of general outline found among leaf-blades. We 
may, however, distinguish between forms of fairly equal breadth, 
or broadest in the middle, and those with broader base or apex. 
J, 
N 
Fig. 14.--Oblong Fig. 15.—Spathulate and Fig. 16.—Rounded and 
Leaf. Oval Leaves. Arrow-shaped Leaves. 
In the first case, we can gradually pass from the needles of the 
fir to broader grass leaves, and so through oblong (fig. 14), oval 
(fig. 15), and rounded (fig. 16) forms to circular ones (fig. 17). 
Where the blade is broader at the base, the form may distantly 
resemble that of a lance-head, an egg, &c., hence receiving the 
name of lanceolate (fig. 18), ovate (fig. 19), &c. Very commonly 
the base is notched, and projects on either side of the leaf-stalk 
_ as amore or less prominent lobe of various form. Heart-shaped 
