LEAVES. 
45 
ions, which do not again unite, as in the crjptogamous plants, 
of which the fern is an example. Heticulate^eined leaves are 
divided into the feather-reined^ as the chestnut, and radiate- 
veined^ as the maple. 
54. Form of Leaves. — Leaves are simple or comjpomid. A 
simple leaf is when the lamina consists of a single piece. A 
compound leaf consists of several parts, each of which is articu- 
lated with the common petiole, in the same manner as the lat- 
ter is connected with the stem. The parts of a compound leaf 
are leaflets^ or folioles. The shape and outline of leaves are 
found to depend chiefly upon the arrangement of the frame- 
work or vascular portion. The form of leaves is expressed by 
terms borrowed from the names of different objects ; as pair 
m-ate^ hand-shaped ; digitate^ from digitus, the finger, &c. 
Of simple leaves there are as fol- Fig> 38. 
lows : a. Orbicxdar, or the round 
leaf, — as in the Nasturtion (See Fig. 
88, a) ; this is also peltate, having its 
f)etiole inserted into the center of the 
eaf, and thus resembling a shield. 
It is radiately-veined, and reticu- 
late. 
b. Reniform (from the Latin ren, 
the kidney), or, as it is sometimes 
called, kidney-form; the ground-ivy {Glechoma) has a leaf of this kind (See Fig. 
38, b) ; it is crenate, or has a margin with scalloped divisions ; ciliate, being fringed 
with hairs, like eyelashes. The venation is radiate and reticulate. 
c. Cordate (from cor, the heart), or heart-shaped. Fig. 38, c, represents a cordate 
leaf with an acuminated point, that is, acute and turned to one side ; the margin ia 
serrated, or notched like the teeth of a saw ; this kind of leaf may be seen in the 
Aster cordifolium, or aster with a heart-shaped leaf. Some of the lower leaves ar« 
curved backward, and then upward 
d, Onate, obovate, 
oval ; these are terms 
derived from 
ovum,im eg^ 
the figure 
represent an 
the broad end we add 
a petiole, prolonging it 
into a mid-rib with some lateral divisions, we have, as at b, the representation oi 
an ovate leaf. If the petiole were placed at Yig. 40. 
the narrowest end, it would be an obovate leaf. 
An oval leaf (c), is when both the ends are of 
equal breadth. When the length is much 
greater than the breadth, the leaf is said to 
be elliptical, as at d. In the ovate leaf, the 
veins next the base are longest ; in the obovate 
leaf, those at the apex are longest ; in the ellip- 
tical leaf they are curved ; thus the outline of 
the leaf varies according to the mode and de- 
gree of the spreading of the veins. 
€. Laweolate (Fig. 40, a) : this kind of leaf 
may be seen in the peach-tree ; it is acuminate. 
2 are terms — v 
im the Latin ^ j 
^. Suppose / y 
at 39, a, to f / 
n egg ; if to 
5*. Forms of leaves— a. Orbicular— J. Reniform— c. Cordate- d. Ovate— Obovate— Oval— Elliptical, 
