TOWN PLANTING, AND THE TREES AND SHRUBS THAT ARE BEST ADAPTED FOR SMOKY
LOCALITIES
Probably no work connected with horticulture requires more judgment
and good management than the planting of trees and shrubs in urban
districts. The materials and soil of which streets and town gardens
are usually formed are ill-fitted for maintaining a healthy condition
in trees and shrubs for any length of time. This fact, coupled with
the impurities of the atmosphere in densely populated centres, has to
be constantly borne in mind. In more favourable districts all that is
necessary is to open a pit of sufficient size to contain the roots of
the tree or shrub to be planted; but in towns the soil, often as hard
as iron and composed mainly of refuse building materials, contains
but little plant food. For many years past careful observations have
been made, not only in London, but in Glasgow, Liverpool, Manchester,
Warrington and Dublin, as to which trees and shrubs succeed best in the
smoky localities of each town, and it is mainly by tabulating these
different experiences that satisfactory information on the subject
has been obtained. Coal smoke from the chimneys in the larger and
more crowded centres of industry is no doubt bad enough, but, when we
have to contend with an atmosphere that is largely impregnated with
the outcome from chemical, gas, or iron works, the difficulties to be
encountered are correspondingly increased.
The injurious effects of smoke have become much more pronounced during
the past century, and Sir William Richmond, R.A., told the annual
meeting of the Coal Smoke Abatement Society that Westminster Abbey
had suffered from more rapid decay in the last hundred years than in
all the previous centuries of its existence. The chief cause of the
destruction of the stonework has been shown to be the presence in the
air of sulphur acids: the stone is converted into sulphate of lime; in
the process of its formation this disintegrates the stone by expansion.
The connexion between smoke and stone decay appears to lie in the
action of invisible gases emitted from the smoke particles.
If stonework suffers so at the hands of smoke and sulphuric and other
acids, what, it may be asked, must the effect be on the foliage
of trees and shrubs—particularly such as are planted in the most
smoke-infested parts of our great towns and cities? When compared
with Continental cities—Paris, Brussels or Berlin—where tree-culture
is carried out most successfully, the atmosphere of British towns is
impregnated to a far greater extent with noxious fumes. Dry low-lying
and confined areas, particularly where excessive heat and atmospheric
impurities are present, are decidedly the worst, while open and
high-lying districts, though in the centre of a town, offer fewer
difficulties.
That certain trees and shrubs succeed best in particular towns is
a well known fact, and the smoke-proof London Plane is by no means
the best tree for some of the colliery districts; in Sheffield,
for instance, its place is largely taken by the Canadian Poplar.
In Manchester, the Lime would appear to thrive best, after which
the Elder, Thorn and Plane succeed in the order named. The
variegated-leaved Sycamore and the horse chestnut are favourites where
the smoke from collieries is most offensive. But many such cases
could be pointed out, and even in the case of bedding plants certain
species succeed best in particular localities. In the gardens about
the Royal Mint, where they are exposed to the deleterious fumes from
gold-refining works, Fuchsias do remarkably well; indeed, the dwarf
edging variety, Golden Treasure, thrives so well that advantage has
been taken of the fact to propagate some of the stock that is annually
required for one of the London parks from cuttings taken at the Mint.
In the East End of London the Creeping Jenny (_Lysimachia_) thrives
well as a window plant, while in the chemically impure atmosphere of
Lambeth one of the Veronicas is the favourite plant for indoor culture.
The St. John’s Worts (_Hypericum_) do not as a rule thrive well in
London; yet around the Tate Gallery, which is only divided by the
river from the Lambeth pottery district—the worst in the metropolis
for atmospheric impurities—one species at least flourishes amazingly,
and has produced flowers in abundance for many years past; while at
St. Paul’s Churchyard, the lesser Periwinkle (_Vinca minor_) has
become quite established and runs about freely. In Chancery Lane, at
the Record Office, the common Ivy, Bladder Senna, and Yucca do best.
In other parts of London, too, well known varieties of Campanula are
largely grown as pot plants. It is a somewhat strange fact, too,
that some varieties of trees and shrubs succeed better than the type
species in smoky localities, as witness the London Plane (a variety
of _Platanus orientalis_), variegated-leaved Sycamore, fastigiate
Poplar, two varieties of Pyrus, Weeping Elm, Weeping Ash, and several
varieties of Acacia, notably _Robinia pseudo-acacia inermis_ and _R.
pseudo-acacia Bessoniana_.
Similarly, amongst shrubs, we have the dwarf Holly, golden variegated
Euonymus, golden Privet, Ribes, double-flowered Gorse, _Euonymus
radicans variegata_, and others. With Grasses, too, some curious
experiences might be related. At the British Museum the Yarrow
completely ousted the Grasses from the plots in front of that building,
and in the moat of the Tower of London several Grasses that succeed
in less smoky parts of the metropolis quickly die out. Near the main
entrance to the Tower of London, and close to Billingsgate Fish Market,
considerable difficulty was experienced in getting the Plane trees
established; though in the matter of soil, and choice of strong sturdy
specimens, every possible care was taken. At last it was found that
the drip from the fish carts was the cause of the evil, and a remedy
was quickly found. In another garden, where dust, smoke, and soot
are plentiful, the Bladder Campion (_Silene inflata_), _Saponaria
officinalis_, the common Marigold, and Rye Grass seem positively to
revel. In situations almost constantly subjected to the sulphurous
fumes of the railway engines near Camden Town, and in the poorest of
soils, _Poa annua_ would appear to be quite at home. The chemical fumes
from the pottery works at Lambeth are well known to act injuriously
on vegetation generally, but the Mulberry, Fig, Sycamore, Turkey and
Evergreen Oaks thrive as well there as they do in any part of the
metropolis. The fumes given off from many of our city manufactories act
most perniciously on vegetation generally—a fact that was brought to my
notice by the behaviour of some of our most valuable smoke-resisting
trees and shrubs planted in the graveyard at St. Giles-in-the-Fields.
Meeting the gardener there I remarked on the wretched condition of the
trees and shrubs generally, his quick reply being, “Well! with Crosse &
Blackwell’s on the one side, and Nixey’s Black Lead Works on the other,
it’s a wonder there’s a living plant left!” Here the common Fig and
Black Poplar seemed better able to withstand the atmospheric conditions
than either the London Plane or Acacia. With the largely increased
use of coal gas for cooking purposes, improved grates, and the better
combustion of fuel, the atmosphere of certain districts of London,
has, however, become much less smoky than was the case a few years
ago, and in consequence vegetation generally succeeds better. This is
especially the case in some of the low-lying districts adjoining the
Thames where the “slot” system of providing gas for cooking purposes
has caused a great decrease in the consumption of coke and coal, with
a corresponding reduction of the attending evils of smoke and soot.
In one of the poorest parishes many of the inhabitants have taken
advantage of the facilities offered by the Gas Company in the matter
of cooking by means of gas provided by the “slot” system, which, in
comparison with coal, has been found not only cheaper, but cleaner
and handier to use. According to a competent authority the smoke
nuisance has, in consequence, greatly abated, and with the purer air,
the cultivation of window and other plants, as well as of trees and
shrubs, has been to some extent simplified. The electrification of the
Underground Railway has also had a beneficial effect on vegetation.
Although we cannot prevent fog, which is an atmospheric condition, yet
much can be done to prevent it being a dirty fog, and during the past
five years much has been done in that direction. Better roads with less
dust also assist largely in keeping the atmosphere of London in a pure
condition.
With the rage for coniferous trees which was at its height about half a
century ago, it is not surprising that several species of Cypress and
Cedar, the stately Pines and Arbor vitæs, as also the Araucaria and
Junipers, found their way into our town gardens and squares. Hosts of
evergreens, too, from almost every part of the world were introduced
into London, but few have been able to survive the smoky and otherwise
impure atmosphere of the great metropolis.
Deciduous trees and shrubs, both flowering and ornamental-leaved,
should certainly be regarded as the _sine qua non_ of the London
planter. Amongst evergreen trees few are suitable for town planting,
and, though a limited number of evergreen shrubs may succeed for a
time, yet the list of deciduous species is far more extensive. We have
only to take notice of such evergreens as the Holly, Rhododendron,
Laurel and all the conifers, with probably one exception, to find
how useless it is to plant them in expectation that they will give
satisfaction. This is not hard to account for, as in winter, when the
fires are all alight and smoke and soot the order of the day, the
leaves of evergreens are fully developed and in the best possible
condition for reaping the attending disadvantages. With deciduous
species the case is quite different, for these are, so to speak, asleep
when the deadly smoke and vapours are most abundant in our towns and
cities. I am quite aware that one occasionally sees evergreen shrubs
and trees in a fairly thriving condition; but it should be remembered
that in the majority of such cases they were planted when conditions
were much more favourable than at present.
It is, perhaps, to be regretted that evergreen shrubs do not succeed
better in smoky localities, being planted principally for their
refreshing colour in winter; but if our atmospheric conditions utterly
preclude the use of such, then it is folly to throw away money on
useless planting, and the winter aspect of deciduous trees and shrubs
is infinitely preferable to that of unhealthy evergreens. The bursting
into leaf of the deciduous tree or shrub is not shared to a like extent
by evergreens, which lack that delightful changeableness and the
interest that is attached to spring growth.
It is difficult to define accurately the boundaries of a town or
the worst smoke-infested areas, as far as tree and shrub growth is
concerned. In London, for instance, certain trees and shrubs which
positively refuse to live in the heart of the city do fairly well
in the suburbs, while still further out, where the atmosphere is
comparatively pure, they may thrive in quite a satisfactory way. These
thriving and non-thriving areas are sometimes very sharply defined,
and this has given rise to a false idea regarding certain trees and
shrubs that will rarely succeed in the more smoky parts when compared
with the same species which are found to do well in the outer suburbs.
High-lying and fairly open parts of a town are also far more conducive
to plant growth generally than those that are close and confined. In
town planting there is, however, no necessity for the almost monotonous
repetition of such trees as the Plane and Lime, or amongst shrubs, of
the Privet and Lilac, for there are many others that will do almost
equally well, and that are quite as ornamental. Probably the fact that
such are not well known would form an excuse for their absence, and
it is to be hoped that at least one object to be accomplished by the
writing of this book will be a greater interest in, and wider knowledge
of, the various species of trees, shrubs, and plants generally that
from long experience have been found suitable for planting in the town
garden.
=Preparation of the Ground.=—Generally speaking, the materials with
which roadways are made are not only unsuitable for tree cultivation,
but positively destructive to vegetation of almost every description.
This also applies to our squares, terraces, and open grounds around
houses, the soil of which is little other than refuse building
materials, and mainly composed of broken bricks and stones, gravel,
old mortar, iron, wood and shavings. In such a medium it is perfectly
useless to look for that healthy and vigorous growth which is so
essential in street trees, that are still further handicapped by having
to do battle above ground with the impurities of a town atmosphere.
Having for a number of years had to plant trees and shrubs in
many parts of London, it was found that in nearly every instance
substituting good soil for that found naturally was a first necessity.
Many failures in street planting from this neglect of providing
suitable soil could be pointed out, the result being that a section
of the public has become tired of the subject in consequence of the
initial expense and subsequent failures. Too often, also, the important
operations of preparing the ground and planting the trees are left in
the hands of the surveyor or builder, who has little or no knowledge
to fit him for the work, the operation being carried out by labourers
who are also entirely ignorant of what is required or the conditions
necessary for successful tree and shrub culture. The consequence is
that failure is almost certain, and the trees which were strong and
healthy when planted gradually become unhealthy and ultimately succumb
to a combination of circumstances which were brought about by the
ignorance of the operators.
Another source of failure in street planting is the generally pent-up
condition of the roots, for in several cases that have come under our
notice lately the planter seemed to think that it was quite enough to
cut a small hole in the pavement or street of sufficient size to hold
the roots of the tree to be inserted. Were the soil free, as we find
in a field, this system might answer; but where the roadway is hard as
iron and composed mainly of clinkers and gravel, the case is totally
different. Another fruitful source of failure in street planting
is placing the pavement in too close proximity to the stem of the
tree, and numerous instances could be pointed out where even old and
established specimens have suffered irreparable damage in consequence
of having the paving brought up too close to the stems.
The roots should always be allowed plenty of breathing room, and
to affect this a good-sized space should be railed off around each
tree and no pavement laid within it. Gratings may be placed on the
surface of the ground around the tree, should circumstances compel
such a course. By adopting either plan, a double benefit to the trees
is brought about by allowing free access of water to the roots and
preventing an accumulation of noxious gases in the soil, as would ensue
if the flagstone or pavements were used.
Where street trees are to be planted, the ground-surface should
in every instance be thoroughly broken up for a space of not less
than 8 ft. square, and to a depth of, say, 4 ft., the inferior soil
removed and replaced by that of good quality, preferably of a loamy
description, or loam and leaf soil in about equal proportions. Before
placing the fresh soil in position, the sides and bottom of each pit
should be thoroughly loosened with a pick or fork. By undermining the
sides of each pit, a much larger and freer root run will be provided,
and this will not necessitate so much of the street or pavement being
torn up as if the pits were of equal width at the top and bottom. We
have found, in London at least, that the addition of a small quantity
of leaf soil to the loam is highly beneficial to the growth of trees
by retaining dampness and encouraging root spread. The newly added
soil should be firmly trampled in the pit before planting is engaged
in. Sometimes, where the original soil is not of too inferior quality,
a small proportion has been mixed with the loam and leaf soil, but,
speaking generally, this course cannot be adopted.
In squares and gardens where shrub planting is to be engaged in,
a general renovation of the soil is also imperative, and this can
best be done by thoroughly trenching the soil to a depth of, say, 4
ft. and adding a large proportion of fresh loam or other soil. Deep
trenching and thoroughly breaking up and loosening the soil is a most
important factor in town planting, and should never be neglected.
Manure is sometimes added to the soil, but it is objectionable from
several points of view, and, if used at all, should be thoroughly
decomposed and incorporated in small quantity. Good loam and leaf soil
is infinitely preferable, and, where necessary, sandy soil makes a
good addition. A little fresh lime added to the soil has been found
most beneficial in town planting, and in old and exhausted borders,
where the soil has become tainted with chemical impurities, the value
of lime or chalk as a cleansing agent is not sufficiently appreciated.
Of course, where so-called American shrubs are to be planted—which is,
however, rarely attempted in London—neither chalk nor lime should be
added to the soil. This question of soil is so important that no one
planting street trees or shrubs can afford to ignore it, and while the
extra cost in providing it is but little, the advantages gained are
great.
=Preparing the Trees and Planting.=—Trees intended for planting in
towns, and especially alongside streets and footpaths, should be
specially prepared in the matter of transplanting and pruning. As tree
guards are a necessity in protecting trees by the sides of streets,
the trees must have their stems free of branches; therefore the buds
and branches on the stems need to be removed for a distance of 6 or
7 ft., whilst surplus leading shoots and ungainly branches should at
the same time receive attention in pruning. The tree also needs to be
frequently transplanted in order that an abundance of fibrous roots
may be produced, and every effort made to produce healthy, vigorous
specimens suitable for the uncongenial surroundings of their permanent
quarters. In street planting it is advisable to use trees that are from
12 to 14 ft. in height; and if these, for some years previously to
their final shift, have been specially prepared in the way of frequent
transplanting and careful pruning, little fear for their future
welfare need be entertained. Autumn or early spring planting is to be
recommended, the former time being in most cases preferable. As little
time as possible should be allowed to elapse between the lifting of the
tree in the nursery and its being transplanted in the new position.
Spread the roots out to their full extent around the stem and avoid
planting too deeply; the nursery mark on the stem serves as the best
guide as to the depth at which to plant. Planting too deeply under
the mistaken idea that doing so will secure the tree in the ground is
a fruitful source of decay and ultimate death of many street trees
planted in the metropolis, and it is not uncommon to see whole avenues
of trees that have made little or no progress for many years owing to
this cause. After a tree has been placed in an upright position on
the prepared site and the roots properly disposed, the soil should be
filled in and trampled firmly both amongst and over the roots. It may
be well to warn planters against the pernicious practice of allowing
leaves, packing materials, or grassy turf to come in contact with the
roots of newly-planted trees. In dry situations a saucer-shaped hollow
may be left around the stem of the newly-planted tree, while mulching
applied during dry and warm summers is to be recommended. The planting
of shrubs should be carried out with as much care as is used in the
case of trees. It is preferable to trench land in which shrubs are to
be planted rather than to make a separate pit for each shrub.
Street trees should be carefully matched—that is, those of similar
height and shape used in the same street. Too often this principle is
not observed, as in a new street near the Strand, where some of the
specimens are about 10 ft. high, others, 15 ft. and 20 ft. high—forming
a very irregular, badly matched row. Many newly-planted town trees are
destitute of leading shoots and have ungainly side branches—faults that
should never be permitted when choosing specimens for such an important
purpose. In choosing trees for street planting, the following rules
should be observed:—
1. Stout, healthy, well-rooted and recently transplanted trees should
alone be chosen.
2. They should, for the same street, be of nearly equal height and
branch spread.
3. Straight-stemmed trees, with stout leading shoots, are to be
preferred.
4. The height should range from, say, 12 ft. to 14 ft. or over, and the
strength of stem should be proportionate to the height.
5. Trees with wand-like, crooked, or cankered stems should be avoided
in street planting.
6. They should be beautiful, shade-giving, and easy of culture.
=Fencing and Staking.=—In order to prevent damage, newly-planted trees
should be fenced and staked at once. Of fences or guards there are
many kinds: they are made of wood, wire or iron. The iron tree guard
has many advantages over those of wood or expanded metal, and, being
made in two sections, it can be readily placed in position after the
tree has been planted. For trees from 12 to 14 ft. high the guards
need not exceed, say, 7 ft. in height, and preference should be given
to those in which the uprights are bent outwards at the top; for this
not only lessens the risk of interference with the branches, but is
pleasing in appearance. Sometimes it may not be considered necessary to
protect town trees, particularly such as are growing in side streets,
or in squares, but in every case firm staking is necessary in order to
prevent damage from wind.
Wooden tree guards consist of about half a dozen poles or uprights,
about 7 ft. long, joined together around the tree trunk by means of
wire. When compared with those of iron, they have, however, several
disadvantages; for they may be climbed with ease and they do not last
long. Where it is found sufficient to stake the trees without having
recourse to guards, ash poles, from 2 in. to 3 in. in diameter, and 10
ft. high, should be driven firmly into the ground as close to the stem
as possible. The tree should be tied with specially prepared tar rope,
which should be crossed between the stem and stake to prevent damage
by chafing. From time to time it will be necessary to see that the
band of string does not become too tight. On rare occasions only is it
necessary to stake shrubs, but this is sometimes advisable in exposed
positions or in the case of shrubs of unusually large size.
=Watering and After-Management.=—For a few years after being planted,
trees and shrubs will require a certain amount of attention in the
matter of watering and mulching during the prolonged heat and drought,
and also in preventing the evils attending excessive wind-swaying owing
to the stakes and moorings becoming defective.
The goat and wood leopard moth, as also numerous kinds of caterpillars,
attack newly-planted town trees, particularly the various species of
Pyrus, Thorn, Willow and Poplar. The former tunnel into the main stem
and render it so weak at the point attacked that it readily breaks
across during windy weather, while the caterpillars feed on the
foliage and greatly impair the health of the trees attacked. Spraying,
hand-picking and shaking are to be recommended in the case of the
caterpillars, while, to combat the goat and leopard moth, a small
quantity of cyanide of potassium can be inserted in the mouth of the
tunnel in order to dislodge or kill the insect.
Watering should preferably be performed in the evening, the ground
around the roots being thoroughly soaked, while mulching with
freshly-mown grass or old straw will prevent the too rapid evaporation
of the moisture. In extreme cases binding the stem with a hay rope is
to be recommended. In order to prevent straining of the roots and bark
chafing, the moorings of trees should receive a periodical examination.
The following trees and shrubs are to be recommended for town planting:—
[Illustration: PLANE TREE IN REGENT’S PARK]
TREES
The =Oriental= or =Common London Plane= (_Platanus orientalis
acerifolia_).—This variety of the oriental plane stands first in the
category of select town trees. Not only does it grow vigorously in
towns, but it is peculiarly well adapted for withstanding smoke and
other impurities of the atmosphere. Repeated experiments have clearly
proved that in London this tree flourishes better than any other, and
a visit to the Thames Embankment and several of the urban districts
will substantiate the statement; while the fine old tree which still
exists in Cheapside, and the equally beautiful specimen which has
hardly room for perfect development in the Court of Stationers’ Hall,
Ludgate Hill, afford other examples of how well suited this handsome
tree is for doing battle with the adverse conditions peculiar to the
great metropolis. As a diversity of opinion has existed about which
variety of plane it is that grows with such vigour in and around
London, it may be stated that, on a careful examination of a large
number of specimens, the variety _P.O. acerifolia_ was found not only
more commonly distributed, but, likewise, better suited for town
planting than the typical _P. orientalis_. This valuable variety is
readily distinguished from the normal plant by the less deeply divided
leaves, and from the American plane (_P. occidentalis_), with which it
is sometimes confounded, by the many fruit “balls” which are attached
to each peduncle, the fertile catkins of _P. occidentalis_ being, for
the greater part, produced singly.
But not only for its value as a town tree is the oriental plane much
sought after, but the giant proportions to which it attains, coupled
with the handsome, finely-cut leaves and easy habit of growth, render
it one of our most desirable ornamental trees. Further, it is of the
easiest culture, succeeding extremely well in soils of very opposite
qualities. Taking everything into consideration, we question whether
any other of our forest trees is equal in value to the plane for
purposes of town planting.
The =Maidenhair Tree= (_Ginkgo biloba_).—The maidenhair or ginkgo
tree is one of the most valuable that can be planted in the impure
atmosphere of a town garden. Few trees can compare with the one
in question for withstanding the deleterious effects produced on
vegetation generally by coming in too close contact with the impurities
of our great centres of industry. The ample delicate-green foliage
betrays—even late in the season, and when about to be cast off—little
evidence of the fierce struggle that must almost constantly go on
between vegetation and the smoke and filth of our towns and cities.
That the thick, leathery leaves and strong constitution of the tree
play an important part in keeping it free from disease is clearly
evident, while the annual renewal of the leaves enables it to cast off
the sooty nodules which work such havoc on the tender foliage of most
evergreen trees.
At several places in and around the great metropolis—and in places,
too, where one is almost stifled with the fumes from chimneys—this tree
may be seen in almost as fresh a condition as those in the open country.
The =Ailanthus= or =Tree of Heaven= (_Ailanthus glandulosa_) may be
seen in a very flourishing condition in many of the largest centres
of industry in Southern England. It has been largely planted in many
Continental cities, and has proved itself one of the few trees that is
capable of withstanding the impurities of a town atmosphere.
The =Black Italian Poplar= (_Populus monilifera_).—Next to the plane
amongst forest trees I consider the black Italian Poplar to be the
most valuable for planting in smoky towns. As a proof of this there
are to be seen numerous fine specimens of this tree in a flourishing
condition, and clothed with the most healthy foliage, in some of our
large cities—to wit, London, Glasgow, Liverpool and Manchester.
The =Canadian Poplar= (_P. canadensis_), and its variety, _P.C. nova_,
are excellent trees for planting in smoky localities. The former
succeeds admirably in the very centre of Sheffield, in the old parish
churchyard, where for hundreds of yards around not a particle of
living vegetation is to be seen. The variety _nova_ is a very superior
tree for street planting, it being far more ornamental, and of more
rapid growth than the black Italian poplar, and equally noticeable
for retaining a healthy and flourishing condition under the adverse
circumstances connected with a town atmosphere.
The =Abele Poplar= (_P. alba_) grows with great freedom when subjected
to smoke and foul air. In the very heart of our largest towns it may be
seen flourishing in a manner that is almost incredible.
The =Lombardy Poplar= (_P. fastigiata_) is another tree that has been
planted with some success in and around many of our largest cities,
but it cannot equal any of the foregoing for withstanding the baneful
effects of a tainted atmosphere. In the outskirts of towns, where air
is purer than amid chimneys pouring forth their volumes of smoke, the
Lombardy poplar succeeds fairly well, and imparts an air of grandeur
that could hardly otherwise be obtained.
The =Cucumber Tree= (_Magnolia acuminata_).—Few planters are aware of
how valuable this tree is for withstanding the germs and soot of large
towns. Experiments have, however, resulted in this highly ornamental
tree being added to the list.
The =Tulip Tree= (_Liriodendron tulipifera_).—Excellent examples are
not wanting of how valuable a tree this is for towns and streets.
It seems to have a wonderful recuperative power, for, scorched,
blackened, and encrusted as may appear the falling foliage, yet in the
following spring it again puts forth a garb of the freshest and richest
greenery. The remarkable four-lobed, truncate leaves render the tree
almost without an equal for ornamental planting, while its undoubted
smoke-resisting qualities place it high in the rank among town trees.
The =Indian Bean= (_Catalpa bignonioides_).—For various reasons
this fast-growing tree is to be recommended for planting in smoky
localities. It grows with great vigour in many smoky centres of
industry, is a tree of handsome proportions, and, when fully
established, flowers freely.
A valuable trait in the character of the Indian bean is that should
accident befall it, and the stem get injured, numerous strong suckers
are produced, which, as they grow with great rapidity, soon take the
place of the original.
The =Common Mulberry= (_Morus nigra_) and the =white-fruited Mulberry=
(_M. alba_) may be seen growing satisfactorily in several of the old
gardens and nurseries of the metropolis, where they are now buried
alive, as might be said, in stones and mortar. That they are excellent
town trees will be admitted by every one who sees the fine specimens in
Liverpool and Manchester.
The =Honey Locust= (_Gleditschia triacanthos_) is a very suitable
subject for planting in smoky localities. In many of the worst
smoke-infested parts of London and Manchester are seen goodly specimens
of this handsome tree—not poor, miserable trees, but, from their great
size, wealth of foliage, and general appearance, betokening perfect
health amid their rather adverse surroundings.
The =False Acacia= (_Robinia Pseudo-acacia_).—Almost by the hundred
can the false acacia be seen in London and many other English towns,
thus proving that it is one of the most valuable trees that we possess
for withstanding the injurious effects of an impure atmosphere.
What renders this acacia of greatest value as a town tree is that it
retains its rich verdure till well on in autumn. The varieties known as
=Decaisneana=, =inermis=, =microphylla=, =macrophylla=, =sophoræfolia=,
and the upright-habited are most to be desired.
[Illustration: THE BEAM TREE IN LONDON]
The =White Beam Tree= (_Pyrus Aria_).—In many of the confined spaces in
Glasgow the white beam tree grows luxuriously, and produces annually
great quantities of its brightly-tinted berries.
The =Lime= (_Tilia europæa_).—Where the situation is not too confined,
and where soot and smoke do not abound, the lime may, and does,
succeed; but in the worst parts of the metropolis it soon shows signs
of distress, the tops of the branches dying off, and the whole tree
sooner or later showing the fierce struggle it has to endure with smoke
and fumes. As an avenue tree in the more airy and pure parts of a
town, the lime has certainly few equals, its general contour and the
pleasing shade it affords being points of special recommendation.
The =Sycamore= (_Acer pseudo-platanus_).—This tree may be classed as
amongst the most useful for planting in smoky towns.
In Warrington, where the noxious emanations from alkali and other
chemical works are most disastrous in their effects on vegetation, the
sycamore is one of the few trees that grow satisfactorily. Being a
rapid and strong grower, it is thus seen to be, for a certain time at
least, unaffected by its inimical surroundings. The variegated variety
would seem from recent experiments to be preferable, and better adapted
for smoky localities than the normal form.
The =Weeping Ash= (_Fraxinus excelsior pendula_) would seem to
be superior to the common ash for planting in towns. It thrives
satisfactorily in many of our largest centres of industry—to wit,
London, Liverpool, Glasgow and Manchester.
The =Horse Chestnut= (_Æsculus hippocastanum_) may be seen in a fairly
satisfactory way in many town parks, but only where it is not exposed
to smoke and soot to any great extent. In confined spaces both it and
the =English Elm= (_Ulmus campestris_) soon show signs of distress,
the points of the branches gradually becoming unhealthy, and the trees
dying off prematurely. Taking everything into consideration, neither
of these trees can be recommended for planting in smoky districts.
The =Birch=, =Walnut=, =Hornbeam=, and one or two kinds of =Willow=
will succeed in the less smoky parts of a town; but they are not to be
recommended for planting where the air is constantly impregnated with
soot and dust.
The =Mountain Ash=, or =Rowan Tree= (_Pyrus aucuparia_) and =Bird
Cherry= (_Cerasus Padus_) are both good town trees, and excellent
examples of both may be seen in the back streets and slums of London.
=Sophora japonica= is well worthy of recommendation as a tree that
is admirably suited for planting in towns. It is of large and rapid
growth, with elegant dark green pinnate leaves. Being a native of China
and Japan, it may not be perfectly hardy in the northern portions
of the British Isles, but it succeeds well in Southern England, and
thrives admirably in the most smoke-infested parts of London.
=Thorns= of various kinds succeed well in towns, but they must not be
recommended for the most smoky and confined localities.
The =Tansy-leaved Thorn= (_Cratægus tanacetifolia_) is an excellent
member of the family for town planting.
SHRUBS
Of these there is rather a long list of kinds that are suitable for
planting in smoky localities.
Evidently deciduous species possess an advantage over evergreen kinds
in the total annual renewal of their leaves, and hence it follows that,
as with trees, deciduous shrubs should have the preference.
The following list includes only such kinds as have been proved
suitable for town planting:—
=Osmanthus ilicifolius= is one of the handsomest of evergreen shrubs,
and also one of the few that succeed, in a satisfactory way, when
subjected to the impurities of a town atmosphere. In the smokiest
districts of both London and Liverpool it is unquestionably the best
all-round shrub.
=Ligustrum coriaceum= is a fitting companion to the last, so far,
at least, as its powers of withstanding the effects of an impure
atmosphere are concerned. Being an evergreen, it is peculiarly well
suited for planting in the town garden, where it grows with great
freedom.
=Olearia Hastii= and =O. macrodonta= are excellent shrubs for the
London garden.
=Aucuba japonica.=—This well-known evergreen shrub is of great value
for planting in urban districts, it being able to do battle with a more
than ordinary amount of atmospheric impurities. For this reason it has
been largely planted in town squares and gardens, in the most crowded
and densely populated parts.
=Griselinia littoralis.=—Although a little-known evergreen, this is
well suited for town planting, experiments having proved it to be a
most valuable addition to the limited number of shrubs suitable for
such a place.
=Hibiscus Syriacus= is one of the few shrubs that can successfully
battle with an impure atmosphere. It is a shrub which town residents
should plant freely if they have a bit of ground that they want to look
pretty.
The =Warfaring Tree= (_Viburnum lantana_) does not receive that amount
of attention to which on its merits it is entitled. It succeeds well in
some of the most filthy and smoky districts of our largest cities.
The =Venetian Sumach= (_Rhus cotinus_) is a much-neglected shrub, but
for general usefulness it can hardly be surpassed. It is peculiarly
suitable for planting in cities.
The =Stag’s Horn Sumach= (_Rhus typhina_) must, on no account, be
omitted, as it is a shrub of curious appearance and one that thrives
well in soot and dirt.
=Leycesteria formosa= is a capital town plant; this may also be said of
the =Flowering Currant= (_Ribes sanguineum_)—indeed, too much praise
can hardly be bestowed on these shrubs for planting in the town garden
and shrubbery.
=Skimmia japonica= and the =Snowy Mespilus= (_Amelanchier Botryapium_),
too, succeed well in smoke-infested districts; and the various kinds
of Lilac—particularly the Common and Persian—have few equals as town
shrubs.
In the =Kentucky Coffee-Tree= (_Gymnocladus canadensis_) and =Bladder
Senna= (_Colutea arborescens_) will be found two most useful shrubs for
the town garden.
=Phillyrea Vilmoriniana=, =Forsythia viridissima=, and the =Strawberry
Tree= (_Arbutus unedo_) are all more or less suitable for town planting
where the atmospheric conditions are not too seriously affected by
smoke and dust.
The =Double Furse= (_Ulex europæus florepleno_) is one of our
handsomest flowering-shrubs, and a good addition to the list of such as
are suitable for planting in town gardens and squares.
The =Spurge Laurel= (_Daphne laureola_) grows freely in many a town
garden—indeed, it is no uncommon thing to see large and well-balanced
specimens where smoke and filth are the order of the day.
=Cotoneasters= of various kinds succeed well as town plants. Those
to be particularly noted are _C. frigida_, _C. Simonsii_, and _C.
vulgaris_.
=Euonymus japonicus= is another excellent shrub, being almost
smoke-defying.
The double-flowered forms of =Prunus sinensis= and the equally
ornamental =P. triloba= all succeed well as town plants; while the
=Almonds= are quite as good.
=Koelreuteria paniculata=, the =Laurustinus= (_Viburnum tinus_),
=Weigelia rosea=, =W. amabilis=, =Deutzia scabra=, the common =Green
Box=, =Gum Cistus= (_C. ladaniferus_), =Mahonia aquifolia=, =M.
Bealii=, and =M. japonica= are all more or less suitable for town
gardens, but not for those in the most smoke-infested parts. The =Japan
Quince= (_Cydonia japonica_), =Hypericum Nepalense=, and =Euonymus
radicans= all do well when subjected to the town atmosphere.
CLIMBERS
Of shrubs suitable for covering walls, trellises, and arbours, and
able to resist the dire influences of smoke and soot, there are a few
valuable and well-tried kinds.
The =Virginian Creeper= (_Ampelopsis hederacea_) has few equals as
a town plant, thriving successfully in the midst of our busiest
centres of industry. Many instances could be pointed out in which this
handsome climber grows with the greatest freedom in the most impure and
smoke-laden atmosphere.
The =Common Ivy= (_Hedera helix_) is, perhaps, the most valuable of all
climbing plants for using in smoke-infested localities. In some of the
courts near Ludgate Hill, a district of London that is by no means free
from smoke and dust, the ivy climbs houses to a height of 60 ft., and
surprises one by its fresh appearance in such localities.
The =Evergreen=, or =Trumpet=, =Honeysuckle= (_Lonicera sempervirens_)
is another shrub of great merit for town planting, as it thrives well
in confined spaces, and where the atmosphere is very impure.
=Cratægus Pyracantha= is a most valuable wall shrub for the town
garden. It is of free growth, stands smoke well, and is one of the
handsomest berry-bearing plants in cultivation.
=Jasminum nudiflorum= needs little description, as it is one of our
handsomest wall-plants. For smoky districts it is invaluable, blooming
freely when flowers are scarce, and seeming to heed but little the
impurities of a town atmosphere.
[Illustration: THE SAVIN, OR JUNIPER, AS A TOWN SHRUB]
The =Vine= (_Vitis vinifera_) must not be omitted from our list, it
being an excellent plant for withstanding soot, smoke, dust and heat.
CONIFEROUS TREES
Few of these, if any, succeed in a satisfactory way, when constantly
subjected to the impurities of a town atmosphere.
Where the conditions are at all favourable the =Austrian Pine=
(_Pinus austriaca_), =Thyiopsis Dolabrata=, =Toxodium distichum=,
and =Cupressus Lawsoniana= do fairly well, but they are not to be
recommended for general town planting.
=Retinospora plumosa aurea= has stood for many years in one of the
most smoky districts of Glasgow, and at present looks almost as well
as it did when brought from the country, while the =Savin= (_Juniperus
Sabina_) may generally be relied upon.