VI 
OUTLINES OF 
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 blade. 
decurrent , when the edges of the leaf are continued down the stem so as to form 
raised lines or narrow appendages, called wings. 
sheathing, when the base of the blade, or of the more or less expanded petiole, 
forms a vertical sheath round the stem for some distance above the node. 
38. Leaves and flowers are called radical , when inserted on a rhizome or stock, 
or so close to the base of the stem as to appear to proceed from the root, rhizome, 
oiv stock ; cauline, when inserted on a distinct stem. Radical leaves are rosulate 
when they spread in a circle on the ground. 
39. Leaves are 
simple and entire , when the blade consists of a single piece, with the margin 
nowhere indented, simple being used in opposition to compound, entire in opposition 
to dentate , lobed, or divided. 
ciliate , when bordered with thick hairs or fine hair-like teeth. 
dentate or toothed, when the margin is only cut a little way in, into what have 
been compared to teeth. Such leaves are serrate, when the teeth are regular and 
pointed like the teeth of a saw ; crenate, when regular and blunt or rounded (com- 
pared to the battlements of a tower) ; serrulate , and crenulate, when the serratures 
or crenatures are small ; sinuate, when the teeth are broad, not deep, and irregular 
(compared to bays of the coast) ; wavy or undulate, when the edges are not flat, 
but bent up and down (compared to the waves of the sea). 
lobed or cleft, when more deeply indented or divided, but so that the incisions 
do not reach the midrib or petiole. The portions thus divided take the name of 
lobes. When the lobes are narrow and very irregular, the leaves are said to be laci- 
niate. The spaces between the teeth or lobes are called sinuses. 
divided or dissected , 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 leaflets , separate, at least at the fall of the leaf, from the petiole, as the whole 
leaf does from the stem, without tearing. The common stalk upon which the leaf- 
lets are inserted is called the common petiole or the rhachis; the separate stalk of 
each leaflet is a petiolule 
40. Leaves are more or less marked by veins, which, starting from the stalk, 
diverge or branch as the blade widens, and spread all over it more or less visibly. 
The principal ones, when prominent, are often called ribs or nerves , the smaller 
branches only then retaining the name of veins, or the latter are termed veinlets. 
The smaller veins are often connected together like the meshes of a net, they are 
then said to anastomose, and the leaf is said to be reticulate or net-veined. When one 
principal vein runs direct from the stalk towards the summit of the leaf, it is called 
the midrib. When several start from the stalk, diverge slightly without branching, 
and converge again towards the summit, they are said to be parallel, although not 
mathematically so. When 3 or 5 or more ribs or nerves diverge from the base, the 
leaf is said to be 3 -nerved, 5-nerved, etc., but if the lateral ones diverge from the 
midrib a little above the base, the leaf is triplinerved, quintuplinerved , etc. The 
arrangement of the veins of a leaf is called their venation. 
41. The Leaflets, Segments, Lobes, or Veins of leaves are 
pinnate (feathered), when there are several succeeding each other on each side 
of the midrib or petiole, compared to the branches of a feather. A pinnately lobed 
or divided leaf is called lyrate when the terminal lobe or segment is much larger 
and broader than the lateral ones, compared, by a stretch of imagination, to a lyre ; 
rwncinate , when the lateral lobes are curved backwards towards the base of the leaf ; 
pectinate, when the lateral lobes are numerous, narrow, and regular, like the teeth 
of a comb. 
palmate, or digitate , when several diverge from the same point, compared to the 
fingers of the hand. 
ternate, when three only start from the same point, in which case the distinc- 
tion between the palmate and pinnate arrangement often ceases, or can only be 
