OUTLINES OF BOTANY. 
XIX 
of an arrow-head : hastate or halbert-shaped, like the last or auricled, with 
the lobes widely diverging : ohcordate or inversely heart-shaped, which is 
heart-shaped with the notched end at the apex. 
68 . Certain terms belong to the ends alone 3 as emarginate, with a small 
notch at the end : obtuse, blunt: acute, terminating in an acute angle with¬ 
out much tapering : acuminate or pointed, tapering or drawn out into a 
point: mucronate, tipped with an abrupt slender point ( mucro): apiculate, 
tipped with an abrupt minute point, &c. 
69. The real base of the leaf is always at the attachment of the petiole: 
but sometimes, from the extension of the posterior part of the leaf back¬ 
wards and the union of the margins behind the point of attachment, the 
petiole Seems to be fixed to some part of the lower surface, when it is pel¬ 
tate or shield-shaped, as in the Mandrake (p. 21), Water-Shield (p. 22), and 
Water-Lily (p. 23). 
70. The general outline, incision, &c., stands connected, in a good de¬ 
gree, with the mode of distribution of the framework (ribs, veins), or the 
venation. 
71. There are two principal modes of venation, viz.: —1. The parallel- 
veined , or nerved, where the w'oody system of the leaf (55) divides directly 
from the apex of the petiole into simple parallel ribs or veins (called nerves 
by the older botanists) which run to the apex without forking; or some¬ 
times they are given off from a prolongation of the petiole traversing the 
axis of the blade, and thence run parallel to the margins. This mode is near¬ 
ly characteristic of Endogenous Plants (52, and p. 445). 2. The reticulated 
or netted-veined, where the ribs or veins branch and subdivide in various 
ways as they spread through the blade, and the branchlets run together or 
unite with one another ( anastomose ), so as to form a kind of network. 
Such leaves are specially said to be veined or veiny (in contradistinction to 
nerved), and are met with in almost all Exogenous Plants (48). The 
stronger primary divisions of the framework are termed ribs; the smaller, 
veins ; the minuter ramifications, veinlets. 
72. Reticulated or netted-veined leaves present two leading modifica¬ 
tions, viz.: — 1 . the feather-veined or pinnately-veined , where the woody sys¬ 
tem of the petiole is prolonged through the blade in a single rib (the mid¬ 
rib) from the sides of which the veins all spring, as in the Oak, Beech, 
Elm, Apple, &c.: 2. the palmately-veined or radiated-veined, where 3 or 
more ribs of about equal strength spring directly from the apex of the pe¬ 
tiole, making the leaf 3 -ribbed, 5 ribbed, &c., as in the Maple, Bass-wood, 
Currant, &c. When strong lateral ribs proceed from near the base of 
a midrib, the leaf is said to be triple-ribbed, quintuple-ribbed, &c., accord¬ 
ing to their number. 
73. The particular mode of incision and division follows the distribution 
of the ribs and principal veins ; the primary incisions, sinuses, or reenter¬ 
ing angles being directed, in the pinnately-veined leaf, towards the midrib, 
in the palmately-veined, towards the base. Accordingly, the particular mod¬ 
ifications of outline and lobing are accurately expressed by combining the 
terms of venation with those which denote the degree of division; as pin¬ 
nately cleft or pinnatif d, when the incisions of a feather-veined leaf reach 
about halfway to the midrib ; pinnate/y parted, when they almost reach it; 
and pinnately divided, when they quite attain it (65). So, likewise, the 
terms palmately cleft, palmately parted, divided. &c., express the degree 01 
the division of a radiated-veined leaf. By adding also the number of the 
lobes or divisions, the description is made still more complete, as pinnately 
5-parted, palmately 3 -lobed, &c., &c. 
74. When a pinnately-veined leaf becomes compound (61), it will therefore 
necessarily be pinnate, that is, with the leaflets arranged along the sides ot 
the midrib (as in the Rose), which then forms a common petiole (or rachis) ; 
while a palmately veined or radiated leaf becomes palmately compound or 
