1066 
THE GARDENING WORLD. 
December 31, 1904. 
Besides these forms of the general outline of the leaf, 
others are given with reference to the margin of the leaf only, 
such as entire serrate, dentate, crenate, bi-serrate, etc. 
Simple outline drawings show what is intended by these 
various terms. We think the small sketch illustrating a bi- 
serrate leaf might have been improved by making the pri¬ 
mary teeth larger or longer; for instance, the Rose leaf on 
page 41 is really doubly serrated, but the secondary teeth are 
very much shorter than the primary ones and seated upon or 
spring from the latter. As a matter of fact this is usually the 
case where leaves are doubly serrate, and in the Rosaceae it 
is, if not universal, at least the most common form of double 
serratures. 
The apex of the leaf is represented by a series of lines 
worked into one drawing, which is valuable as showing the 
different forms of the apex alongside of one another. It 
would have helped the student, or, at least, the beginner, to 
understand the diagram better if the stalk to the leaf had been 
inserted on the left-hand end of the diagram. Here, again, a 
large number of examples of leaves having some particular 
form of apex are given, so that the student can compare the 
actual leaf with the diagrams to which the technical terms are 
applied. These plants being in most cases quite common leave 
little excuse for the student who does not set himself to master 
the same. 
The question of phillotaxy, or the arrangement of the leaves 
upon the stem, is discussed, though the author does not seem 
to lay any great importance upon it. The simpler forms of 
arrangement are by far the most common, and the more com¬ 
plicated ones merely refer to those in which the leaves are 
small or densely arranged upon the plant, owing to the short¬ 
ness of the intemodes. He also cautions the student to be on 
his guard against confounding phillotaxy with displacements 
that often occur. The term itself is concerned only with the 
positions on which the leaves are attached to the stem. There 
are several causes that co-operate in bringing about changes 
from the normal whereby the actual position of the blade 
bears but little reference to phillotaxy itself. For instance, 
light is the most important factor in the disposition of the leaf- 
blade whereby it may catch a maximum of light without un¬ 
duly shading its neighbours beneath the same. 
If anyone takes the trouble to observe the shoots of the 
Sycamore looking down upon the same as they grow, he will 
see that a considerable number of leaves inserted on various 
positions on the upright shoots are so arranged as to form a 
flat top, this being brought about by the longer stalks pos¬ 
sessed by those leaves on the lower levels of such stems. 
Then, again, what will be even more apparent in the Horse 
Chestnut is that although the leaves are all opposite, those on 
the lower side of the spreading shoots have much longer 
petioles, so as to cany them beyond the leaves on the upper 
side of the shoot, which are not only smaller, but have shorter 
stalks. In a botanic garden or in any good collection of trees 
and shrubs the student will lie able to find many examples of 
this form of arrangement in which light has such an important 
influence upon the leaves as to actually disguise the phillotaxy 
in the eyes of the uninitiated. 
The author says that the laws of phillotaxy have to do with 
space-relations and pressure upon leaves in the bud, with the 
need after expansion for exposing the leaves in the best pos¬ 
sible manner to light. We have a good instance of this in the 
Oak, where the number of leaves, or nodes where they should 
be, in the bud are very great, yet a considerable number of the 
lower ones on the young shoots are not developed while others 
are small. Those which reach full size are mostly arranged 
towards the top of the shoots in many instances, so that they 
may catch a maximum of the rays of light. The leaves when 
they reach full development are therefore few by comparison 
with those originally provided for in the bud. 
In dealing with phillotaxy the author does not overlook the 
fact that some plants have more than one form or plan of 
arrangement the leaves. An instance of this is met with 
in the Laurel Cherry, where the leaves on the erect branches 
are arranged on the 2-5 p hi, while the leaves on horizontal 
branches are distichous on the \ plan. Differences in the 
plan also occur where leaves have become adapted for some 
special purpose. 
Another and irregular kind of discrepancy occurs where the 
leaves may be opposite or alternate on the same branch. 
Other cases of discrepancy are brought about by crowding, dis¬ 
placements, fascicled shoots and leaves, suppression and so 
forth. We think the so-called displacements in the case of the 
Solanaceae are due to the fact that the stem consists of a 
sympodium having a succession of axes arising one above the 
other, while each separate axis ends in an inflorescence as in 
the Tomato or in a bunch of flowers or tendrils in the case of the 
members of the Vine family. In each of these cases, however, 
although the flowers seem to be extra axilliary, they really ter¬ 
minate each a separate axis. It may not follow that an in¬ 
florescence is always produced at the apex of an axis, and the 
small leaf accompanying the large one on a Solarium may 
originally have been of the nature of a bract. The case is 
somewhat complicated, and others may hold a different 
opinion. 
Another interesting feature of the author’s descriptions and 
illustrations is where he takes up the case of leaf-mosaics. The 
leaves belonging to a system of neighbouring branches or even 
upon one branch may be arranged so as to dovetail or fit 
into each other in a remarkable manner with the evident 
object of appropriating all the available space and thus secur¬ 
ing full exposure of each member to the light. This crowding 
and exact fitting of the leaves recalls or suggests inlaid work or 
mosaics. One good example is given of a piece of Ivy pros¬ 
trate upon the ground, but fitting all the leaves so as to com¬ 
pletely cover the ground occupied by them without overlap¬ 
ping one another. Another good example of this is given in 
the case of the English Elm, where the unequal-sided leaves so 
fit one another that one leaf occujnes the sqiace left vacant by 
the oblique side of the other. 
This is very much akin to what we mentioned above hi re¬ 
lation to the terminal and side branches of Maples and Horse 
Chestnut, but many others could be added, including those 
having pinnate leaves as well as simple ones. The Beech is a 
good illustration of the latter, and the student who observes 
these facts and understands their meaning cannot feel sur¬ 
prised that other vegetation refuses to grow under such trees. 
It is not a case of poisoning, but the leaves so occupy the space 
as to throw off the rain beyond the influence of anything be¬ 
neath the tree, and at the same time completely obstruct the 
light necessary to their welfare. 
In dealing with the leaves of Willows, he speaks of Salix 
rubra as if it included only one form. There are, however, two 
distinct British hybrids between S. purpurea and S. viminalis. 
The author’s description in connection with rubra deals only 
with that form having veiy long leaves that are rather silky 
beneath. The other form is really more related to S. pur¬ 
purea, and although some writers speak as though there were 
numerous forms which they place under S. rubra purpureoides, 
Ave think they are only variations in form according to condi¬ 
tions either artificial or natural, and that most or all of them 
can be placed under S. forbyana. On the Avhole, however, Ave 
think that students will find this a very interesting book, re¬ 
cording much original research and observation. 
Protection of Highavay Landscape.— A laAv has been made 
by some of the States of America, including Massachusetts, 
Connecticut, and Rhode Island, which the “ American Botanist 
considers a wise provision for the protection of trees along the 
highways and in situations where they form part of the liigliAvay 
landscape. Each town appoints a tree warder, serving without 
remuneration, who may seal to the town by his label such 
trees as he regards common property, and this, too, without 
regard to whose land they may belong. If the owner of siacIi 
trees may desire to cut one down, he must first obtain permis¬ 
sion, after giving satisfactory reasons at the annual town meet¬ 
ing. The cutting doAvn of trees would therefore become sonie- 
Avhat troublesome to the owner, Avho Avould possibly in many in¬ 
stances leave it alone to escape the inconvenience and trouble 
in connection with the same. 
