INTRODUCTION 
midrib , from which slightly finer transverse secondary veins are given off, 
like the barbs of a feather, whence it is called pinnate, or several principal 
veins radiating from the base of the leaf, like the fingers from the hand, 
whence the name digitate or palmate ; but in either case, as is well seen in 
the leaf of a Primrose or a Sycamore, the finer ultimate branch-veins run 
together at various angles, making a complex and seemingly irregular 
mesh. It will be noticed that the venation largely influences the incision 
of the margin or the branching of leaves. 
No matter how deeply the margin of a leaf may be cut, as in the 
leaves of Buttercups or Dandelions, if the leaf be not divided into distinct 
. . leaflets, separately articulated to the petiole or midrib, it is 
Composition ....... .. . . . . 
termed simple , while according to its venation it may be 
pinnate ly-lobed , as in the Dandelion, or palmately-lobed, as in Buttercups or 
Sycamore. A compound leaf is made up of distinct leaflets and must be 
carefully distinguished from a stem bearing leaves. Unlike a stem, it has 
no growing point, and its leaflets do not bear buds in their axils. It may 
be either palmate , when the leaflets radiate from the apex of the petiole, or 
pinnate , when they are given off - from its prolongation the midrib or 
primary rhachis. Special terms are sometimes used for the ternate leaf, or 
palmate leaf of three leaflets in Clover or Wood-sorrel ; the quinate leaf, with 
five leaflets in Cinquefoil ; or that with seven in the Horse-chestnut. If 
the petiole branches palmately once or twice, only the ultimate branchings 
ending in leaflets, it is termed bi- or tri-pa/mate. The leaf of Baneberry is, 
for example, tri-ternate. The leaflets of pinnate leaves are generally in 
opposite pairs, each pair being termed a jugum , and the number of 
juga ranges from one to a large number ( multi-jugate ), as in some Vetches, 
while alternate juga may be large and small, as in Agrimony, when it is 
called interruptedly pinnate. There is generally a terminal leaflet, as in the 
tri-jugate leaf of the Rose, which is, therefore, termed impari-pinnate , or 
unequally pinnate, though the leaf may, as in the False Acacia, be 
paripinnate , or equally pinnate, i.e. with no terminal leaflet. The leaflets 
of a pinnate leaf are termed pinna ; but if they are themselves branched 
pinnately the leaf is bi- or tri-pinnate , its divisions are known as primary 
XXV 
