INTRODUCTION TO BOTANY. Vv 
Leaves are, 
amplexicaul, or stem-clasping, when the sessile base of the blade is not 
a mere point, but forms more or less of a ring, clasping the stem 
horizontally. 
perfoliate, when the base of the blade not only clasps the stem, but 
closes round it on the opposite side, so that the stem appears to 
pierce through the membrane of the leaf itself. 
decurrent, when the edges of the leaf are continued down the stem, 
so as to form raised lines, or narrow stem-borders called wings. 
sheathing, when the base of the blade, or of the expanded petiole, 
forms a vertical sheath round the stem for some distance above 
the node. 
36. Leaves (and flowers) are called radical, when they spring directly 
from a rhizome or stock, or are inserted so close to the base of a stem as to 
appear to spring from the root or stock. Leaves are cauline, when they 
spring from the main portions of the stem; rameal, when from a branch. 
37. Radical leaves are rosulate, when they spread in a circle on the 
ground; cauline or rameal leaves are fascicled or tufted, when the leaves of 
two or more nodes are brought close together in a pencil-like tuft, by the 
non-development of the internodes; as in Aspalathus, Asparagus, etc. 
38. Leaves are, 
simple and entire, when the blade consists of a single piece, and the 
margin is nowhere indented ; simple being used as the opposite to 
compound, and entire as the opposite to dentate, lobed, or divided. 
ciliate, when bordered with straight hairs, or hair-like teeth; czdio- 
late when the hairs are small. 
dentate, or toothed, when the margin is slightly notched at regular 
distances into what have been compared toteeth. Such leaves 
are serrate when the teeth are poimted like those of a saw; 
crenate, when blunt and rounded. The diminutives serrulate, 
crenulate are used to express minutely serrate or minutely crenate. 
The hollows between the teeth are respectively called serratures 
and crenatures. 
sinuate, when the margin is bluntly indented, with broad, shallow, 
and irregular hollows between the projections (like the bays 
between the headlands of a coast) ; wavy, or undulate, when the 
edges of such a leaf are not flat, but bent up and down (like 
the waves of the sea). The hollows between the projections are 
called sinuses. 
lobed or cleft, when more deeply indented or divided, but so that 
the incisions do not reach the midrib or petiole. The teeth or 
sections of such leaves are called Jobes. 
divided, when the incisions reach the midrib or petiole, but the parts 
so divided off, called segments, do not separate from the petiole, 
even when the leaf falls without tearing. 
compound, when divided to the midrib or petiole, and the parts so 
divided off, called /eaflets, separate, at least on the fall of the 
leaf, from the petiole, as the whole leaf does from the stem, 
without tearing. The petiole of a compound leaf is sometimes 
called the common petiole (because common to all the leaflets, 
which often are united to it by petioles or individual petioles) ; 
sometimes the rachis, a term also applied to the inflorescence 
(67). 
39. Leaves are more or less distinctly marked by veins, which, starting 
from the stalk, diverge or branch as the blade widens, and spread over it 
in various patterns. These veins represent the woody and vascular 
system (170) of the leaf. The principal ones, when prominent, are often 
