and from serious fungoid or insect attacks, it is the host of a
parasitic fungus which seldom fails to make its presence apparent,
though without perceptibly affecting the growth or health of the tree.
Readers must be very familiar with the circular black spots which appear
on the leaves about midsummer and continue till they fall. It is not a
few leaves or a few trees here and there that are so affected, but all
the leaves on large trees and on every tree in the wood. The difficulty
is to find a leaf without these black spots; so that people have come to
regard them as part of the regular colour scheme of the foliage.
Nevertheless, each of these blots is a colony of the parasitic fungus,
_Rhytisma_, whereof the life-history is still subject for investigation.
It is not evident how the colonies are regularly distributed, each clear
of the other, all over the leaves of a lofty tree, nor how, seeing that
they fall to the ground with the leaves in autumn, the fungus manages to
get access in the following summer to the loftiest branches. It is lucky
that, being so widely distributed and existing in such incalculable
numbers, these colonies do not appreciably interfere with the natural
functions of the sycamore.
The only native species of maple in Britain is the Field Maple (_Acer
campestre_), which does not extend naturally into either Scotland or
Ireland, though it grows freely in both these countries when planted in
either of these countries. It is a very ancient element in the woodland
of south Britain, its remains having been identified in pre-glacial beds
in Suffolk. It has no qualities to recommend it for ornamental planting,
and the timber, once highly prized by British cabinetmakers, has been
ousted from the home-market by imported foreign woods. When the Rev.
William Gilpin, author of a well-known work on _Forest Scenery_, died in
1804, he was buried, it is said, at the foot of a field maple growing in
his own churchyard at Boldre, in the New Forest. Strutt gave a figure of
this tree which he described as the largest of the species in England;
but he gives the height as only 45 feet, whereas Elwes records several
from 60 to 70 feet high.
A far more desirable tree than the field maple is the Norway maple (_A.
platanoides_, Linn.). The title "Norway" no more indicates its natural
range than the term "Scots" does that of _Pinus sylvestris_, for this
maple is found in most European countries and as far east as Persia and
the Caucasus. It is a beautiful tree, especially in autumn, when its
foliage takes on brilliant red and yellow hues; but it requires
attention during the first twenty or thirty years of growth, in order to
check its disposition to a straggling branchy habit. If that be stopped
by timely pruning, the Norway maple grows straight and free, attaining,
under favourable conditions, a height of 80 to 90 feet. Its timber has
not the ornamental character of that of field maple, but is said to be
of similar quality to that of sycamore. The petioles or leaf-stalks of
this species contain a milky juice, whereby the tree may be
distinguished from all other members of the genus.
Now, whereas botanists enumerate no fewer than one hundred and ten
species of maple, natives of Europe, Asia and America, it would be
impossible within the limits of this modest volume to discuss even the
most desirable of the genus. Among the North American species there are
several that grow to splendid dimensions in their native forest. One of
the most distinct is the red maple (_A. rubrum_), a beautiful object in
spring when it bears flowers profusely, which, in some varieties, are of
a charming red colour. There are a few specimens in England of the
well-known sugar maple (_A. saccharum_), but it seldom thrives in this
country, though it has been frequently tried since its introduction,
according to Loudon, in 1735.
The Plane
Among Scottish foresters the name "plane-tree" has come to signify the
sycamore; but the sycamore is a kind of maple, whereas the term "plane"
is rightly appropriated to _Platanus_, whereof there are four species,
constituting the natural order of _Platanaceæ_. Of these four species,
three are natives of North America; and forasmuch as none of them has
proved amenable to cultivation in Europe, they may be dismissed with the
remark that one of them, the button-wood (_P. occidentalis_), attains
enormous proportions in its native forests, rising to a height of 170
feet, and with a girth (recorded by Michaux) of 47 feet.
The fourth species (_P. orientalis_) ranks among the noblest hardwoods
of temperate Europe and Asia. Clear among memories of many sylvan scenes
stand a pair of giant planes on the flank of Mount Olympus, in the
leafless branches of which on a bright January morning a pair of
white-tailed eagles monopolised the attention which I was intended by my
Turkish host to devote to woodcocks in the copse below. Those who have
sailed along the Dalmatian coast will doubtless remember the harbour of
Gravosa, and the solitary plane that casts such a grateful shade across
the quay. But one need not go to the Continent for giant planes. In our
day it is one of the trees most commonly planted in the southern
counties for shade and ornament, and has no equal for the smoke-laden
atmosphere of London. It may be that it was one of Evelyn's seedlings
that Bishop Gunning planted in his Garden at Ely between 1674 and 1684.
This tree in 1903 was 104 feet high, with a girth of 20½ feet.
Messrs. Elwes and Henry give a photograph of it in their _Trees of Great
Britain and Ireland_, and consider it to be the largest specimen in our
islands of the cut-leaved variety.
Turner, writing in 1562, mentions "two very young trees" growing in
England, which indicates the middle of the sixteenth century as the
period of its introduction. A hundred years later, Evelyn says he has
raised from seed--
"_Platanus_, that so beautiful and precious tree so doated on by
Xerxes that Ælian and other authors tell us he made halt and stop'd
his prodigious army of seventeen hundred thousand soldiers to
admire the pulchritude and procerity of one of these goodly trees,
and became so fond of it that he cover'd it with gold gemms,
necklaces, scarfs and bracelets, and infinite riches."
The maple-leaved variety, usually known as the London plane, is the sort
most commonly planted in England, and rightly so, for it is more
vigorous than the other. Probably the tallest in England grows at
Woolbeding, in Sussex; it was 110 feet high in 1903, with a girth of 10
feet, and a clean bole of 30 feet. It would be needless to enumerate
the fine planes in and near London; one has only to look at the groups
beside the Admiralty and in Berkeley Square to realise how it thrives in
an atmosphere pernicious to nearly all other forest growths. Fifty or
sixty years hence the avenue of planes planted not long since along the
Mall will be one of the sights of Europe. The skilful way in which they
are being trained each to a single leader gives them a stiff, ungraceful
appearance at present; but this treatment is a bit of true
arboriculture, carried out in the teeth of bitter criticism. "Bairns and
fules shouldna see things half dune."
It is the absence of the conditions specially favourable to the growth
of the plane in London and the south that makes it unsuitable for
planting in the North of England and in Scotland. It is native to a
region of scorching summers; in London the sun's heat is reflected from
buildings and streets in a manner most acceptable to it. It will stand
any amount of frost it may encounter in Scotland; but it pines for want
of summer heat, witness the unhappy condition of those which have been
planted experimentally along the west end of Princes Street, Edinburgh.
I do not know of a single plane of more than mediocre stature north of
the Tweed.
The plane is nearly as late in leafing as the ash and the walnut,
thereby escaping the cruel frosts so characteristic of British spring;
but unlike the ash, it retains its foliage into very late autumn. Pliny
described an evergreen plane growing in Crete; but after the botanist
Tournefort (1656-1708) had searched the island in vain for it, this was
relegated to the category of myths. Howbeit, tardy justice was done to
Pliny as the prince of field naturalists, when in 1865 Captain Spratt,
R.N., was shown two young plane trees, retaining their leaves throughout
the winter, which had sprung from the root of a very large tree that had
been felled. He also heard of two others.
The Oriental plane has not been long enough established with us to give
an estimate of its longevity in Britain. In the Mediterranean region it
attains a vast age. Only a hollow stump remains of one at Vostiza, in
the Gulf of Lepanto, which in 1842 was about 130 feet high and 37 feet 4
inches in girth, and was believed to be the tree described by Pausanias
when writing his description of Greece in the second century after
Christ. Neither have we learnt to make much use of the timber so
plentifully produced by the plane, though it is said to be second to
none for the bodies of carriages.
In antiquity of descent the plane tree has few, if any, superiors among
broad-leaved trees, its remains having been recovered from the
Cretaceous beds of North America, besides numerous species recovered
from Miocene and Tertiary strata, in Northern Europe, whence they were
expelled when that region became icebound.
The London planes have been accused of being chief agents in inflicting
influenza, bronchitis and catarrh upon the inhabitants of the
metropolis. It has been seriously affirmed that when the seed-vessels
of the plane break up in dry spring weather, the air is filled with
minute spicules which act as an irritant upon human throats and noses.
It may be so; but before condemning the trees, without which London
would indeed be desolate, it would be well to ascertain first whether
the ailments referred to are more prevalent in London during the months
when the plane tree is shedding its dry fruit than they are at other
times of the year; and second, whether they are more prevalent in
London, where there is wealth of planes, than they are in cities where
there are no planes, as Edinburgh, Glasgow, Liverpool, Newcastle, etc.
Unless this can be shown to be the case, it is difficult to reconcile
the fact that London has the lowest death-rate among the cities of the
United Kingdom with any mischief arising from the luxuriance of these
beautiful trees.
[Illustration: HORSE CHESTNUT (_Æsculus hippocastanum_) IN BLOOM]
[Illustration: HORSE CHESTNUT FLOWER SPIKE]
The Horse Chestnut
In one respect the horse chestnut (_Æsculus hippocastanum_) may be
reckoned among the most remarkable trees of British woodland, inasmuch
as, although it has been found in a wild state only here and there among
the mountains of Greece and Albania, where it enjoys a climate widely
dissimilar from that of Western Europe, it has a constitution so
cosmopolitan as to become thoroughly at home in all parts of our
country. It thrives as vigorously on the dry chalk soil of Hertfordshire
as on the soaked hillsides of Perthshire, and, given reasonable shelter
from violent winds, produces its magnificent foliage and flowers as
freely near sea level as it does at Invercauld in Aberdeenshire, where
there is, or was not long ago, a fair specimen growing at an elevation
of 1,110 feet, not far short of the practical limit of tree growth in
Scotland. In 1864 this horse chestnut was 8 feet 7 inches in girth, and
was believed to have been planted in the year 1687; therefore, if it
still stands, it is now 226 years old.
Another sign of the adaptability of the horse chestnut to British
environment is the freedom with which it ripens its large fruit and
reproduces itself from self-sown seed wherever it gets a chance. The
facility with which it does so has caused this tree to be deemed
indigenous in many parts of Europe and Asia where it certainly is not a
native, but where it has been planted originally on account of its
beauty. Further confusion has arisen from the botanists Linnæus and De
Candolle having failed to distinguish the Indian horse chestnut (_Æ.
indica_) from the Greek species, and having assigned Northern Asia as
the native region of the latter.
It would not be difficult to mention many individual horse chestnuts in
the British Isles exceeding 100 feet in height; probably this tree, if
subjected to forest conditions, would grow far loftier than that; but,
as it is usually planted exclusively for ornament, it is most often
found standing isolated, thereby receiving encouragement to develop
enormous side branches and to grow in breadth and bulk rather than in
height. Such is the character of a great horse chestnut standing in a
group near Moncrieff House, Perthshire. In 1883 this tree measured no
less than 19 feet in girth at 5 feet from the ground; but at 10 feet it
divides into three huge limbs, each girthing 10 feet, and covers a space
nearly 100 yards in circumference. The soil in this district is cool and
the climate humid, very different from the conditions at Ashridge in
Hertfordshire, where the soil is chalky and hot; yet there is in that
fine park a horse chestnut even more massive than the Moncrieff House
specimen, being about 80 feet high, and measuring 20 feet in girth.
Probably the loftiest horse chestnut in Britain, perhaps in the world,
is one at Petworth, in Sussex, which, having been drawn up in close
forest, now measures between 115 and 120 feet in height.
It is a pity that this noble tree does not more often receive
encouragement to upward growth, seeing that if the surrounding trees are
cleared away judiciously, that is not too suddenly, after the horse
chestnut has reached a good height, it then feathers down in the most
charming manner. It is very seldom that, without discipline of this
kind, it will put its energy into height, and attain the fine
proportions of a specimen at Biel, in East Lothian. In 1884 this grand
tree, probably the loftiest in Scotland, measured 102 feet in height,
with a clean bole of 40 feet. It is worth any amount of trouble to
secure this character in the horse chestnut, which is an inveterate
spreader if allowed licence; and the tendency may be checked by knocking
side buds off the stem in the sapling stage, and timely pruning as the
tree goes on to maturity.
As an avenue tree, the horse chestnut has few, if any, superiors.
Perhaps the finest examples in Scotland of this manner of planting it
are to be seen at Gilmerton, in East Lothian, and Drummond Castle, in
Perthshire; while in England the splendid double avenue at Bushey Park,
Middlesex, has long been famous, "Chestnut Sunday" being a noted
festival for Londoners when the trees are in full bloom. The horse
chestnut, however, is not a long-lived tree, and cannot be reckoned upon
to survive beyond 250 years. The Bushey Park chestnuts are failing
fast, many having died already and been replaced by saplings.
Talking of avenues, it is worth while to note a calamity described by
Mr. Hutchison of Carlowrie in the Transactions of the Highland and
Agricultural Society for 1884. He states there that in 1867 an avenue of
horse chestnuts was planted as an approach to the cemetery of Wimborne,
Dorsetshire, the trees being set 25 feet apart in the rows. In 1875 it
was thought to improve the avenue by planting yews in the intervals
between the chestnuts, which had this unfortunate result, that the
chestnuts, which had previously thriven finely, all pined away and died.
It is on record that the horse chestnut was first brought to France in
1615, and probably found its way into England about the same time. It
seems that it was expected to rank with walnuts and Spanish chestnuts as
a fruit tree, a notion which was speedily dispelled. John Evelyn,
however, with a right taste for sylvan beauty, early discerned its
decorative merit, writing about it in 1663 as follows:
"In the meantime I wish we did more universally propagate the horse
chestnut, which being increased from layers, grows into a goodly
standard, and bears a glorious flower, even in our cold country.
This tree is now all the mode for the avenues to their country
places in France."
Travellers in that fair land will remember with pleasure the fine use
still made of this tree beside some of the high roads. Between Tours and
Blois the wayside has been planted with a chestnut unknown to Evelyn,
for it did not exist anywhere in his day. This is the red horse chestnut
(_Æsculus carnea_), which seems to have originated in Germany about the
beginning of the nineteenth century, and is believed to be a hybrid
between _Æ. hippocastanum_ and the North American shrub _Æ. pavia_. It
is a most beautiful tree, the flowers being of a delightful shade of
bright carmine. We are told not to expect it to attain the stature of
the common horse chestnut, so it would be well, in designing an avenue,
not to mix the red and the white with a view to matching them in height;
but the red hybrid has already risen to 50 feet high at Barton in
Sussex, and I entertain an idea that this tree may develop into larger
proportions than is expected of it, when planted in good soil and
favouring shelter. At all events, some which I planted about thirty
years ago are now quite as large as common horse chestnuts of the same
age.
Mr. Elwes recommends the horse chestnut for planting in towns, remarking
that "next to the plane it is one of the best trees we have for this
purpose, and does not seem to suffer much from smoke." I regret that I
am unable to endorse this view. It is true that in towns of moderate
size, and in country villages, horse chestnuts may be planted with
excellent effect. I know of few more charming sights than is presented
by the group of these trees in the high street of Esher when they are in
flower; but in London horse chestnuts prove a lamentable failure. Living
as I used to do in the neighbourhood of Sloane Street, it was a distress
to me each year to watch the stunted, round-headed chestnuts in the
gardens at the lower part of that thoroughfare, and in Eaton Square,
unfolding their delicate fingers only to have them parched and blackened
by the ruthless drought and dirt of the Metropolis.
As a timber producer, the horse chestnut cannot be assigned high rank.
There is no lack of quantity, for the tree increases very rapidly in
bulk, but in quality the wood is soft, weak, and very perishable.
Moreover, it is almost useless as fuel, and probably the only economic
purpose to which it could be applied profitably is the production of
wood-pulp and celluloid.
The true meaning of the prefix "horse," by which this tree is
distinguished from the true or Spanish chestnut, has been the subject of
much discussion. Apparently it was not applied in the sense of "coarse,
large," as in the terms horse-radish, horse-mushroom, etc., for the
Turkish name for it is _at kastan_, signifying horse-chestnut; and this
was explained in a letter written by the Flemish Dr. Quackleben to
Matthiolus in 1557 (many years before the tree was known in Britain),
explaining the use of the fruit as a specific against broken wind in
horses.
[Illustration: ASPEN TREE (_Populus tremula_)]
The Poplars
"Hard by a poplar shook alway,
All silver green with gnarled bark;
For leagues no other tree did mark
The level waste, the rounding gray."
There is much confusion among the different species of poplar, but it is
clear that in these verses Tennyson had in view our native abele or grey
poplar (_Populus canescens_), a native of Great Britain, often mistaken
for the white poplar (_P. alba_), which nearly resembles the grey, and
has been planted in this country, but is probably an exotic. The poet's
epithet "silver green" admirably describes the foliage of the grey
poplar, for some of the shoots bear green leaves, others white ones,
others again green leaves on the lower part and white on the upper.
Of all known species of poplar, thirty or so in number, the abele
produces the choicest timber, much in request by carriage-builders, who
sometimes pay as much as 2s. 6d. a cubic foot for well-grown logs. It is
excellent timber for flooring bedrooms, being less inflammable than any
other British-grown wood except larch. It is, therefore, characteristic
of British neglect of woodland resources that this tree is hardly ever
planted, though it is most easily propagated from suckers or cuttings,
and attains an immense size long before an oak could reach maturity.
The abele is more common in Scotland than in England, and many large
trees might be mentioned in the North. It would be difficult, however,
to find any to surpass two growing at Mauldslie Castle, in Clydesdale,
one of which in 1911 measured 100 feet high and 21 feet 3 inches in
girth, the other 117 feet by 16 feet 5 inches. It should be noted that
the girth of both was taken at between 2 and 3 feet from the ground,
instead of 5 feet, which is the proper height for measurement.
Next in economic importance to the grey poplar stands what is popularly
known in this country as the black Italian poplar (_P. serotina_), which
is not Italian in any sense, but a hybrid originating in France (where
it is called _peuplier suisse_) between an American species and the true
black poplar (_P. nigra_). This confusion of names is all the more
perplexing because the upright variety of the true black poplar goes by
the name of Lombardy poplar. However, one must use the names most
generally recognised among woodmen, and the black Italian poplar is well
worthy of more attention than it has hitherto received in this country,
for it produces valuable timber in greater bulk in a short term of years
than any other British-grown tree. Mr. Elwes has recorded how thirty
poplars of this variety, planted on cold clay in Gloucestershire, not
worth 5s. an acre, were sold for £3 apiece at forty-eight years of age.
He lays stress on the importance of giving this tree plenty of room at
all stages of growth, planting them at 15 to 20 feet apart, for the
timber is little worth unless the tree gets enough light to enable it to
produce wood rapidly. This precept applies to every species of poplar.
The tallest black Italian poplar in Great Britain is probably one
growing on the banks of the Tillingbourne, in Albury Park, Surrey, which
in 1912 measured 150 feet high, with a girth of 15 feet 3 inches. There
are many fine specimens in Scotland, notably one at Scone Palace, which
in 1904 was 132 feet high, with a girth of 15 feet 4 inches. Another at
Monzie, in Perthshire, measured at the same time, stood 125 feet high.
Turning now to the true black poplar (_Populus nigra_), we find that
this species, a native of Midland England, but probably not of Scotland,
has become established in the eastern United States, having been
introduced there by British colonists. It has often been confused with
the black Italian variety, but may easily be distinguished in this
country by the large burrs on the trunk, by its earlier leafing, and by
the young foliage being green, instead of reddish, as in the black
Italian. The true black poplar also sheds its leaves much earlier in
autumn than does the other. It is not a tree commonly planted in
Scotland, but there are specimens ranging from 90 to 100 feet high at
Dalzell, Ross, and Cambusnethan, in Lanarkshire; at Auchentorlie, on the
Clyde; and at Smeaton-Hepburn, in East Lothian.
The variety of this tree so well known as the Lombardy poplar forms a
notable feature in the landscapes of Southern England, Central and
Southern Europe, and a great part of Asia. As it can only be propagated
by cuttings, it is believed that all the millions of Lombardy poplars
spread over the continents of Europe and Asia originated with a single
"sport" growing on the bank of the river Po early in the eighteenth
century. Probably the first of its race was brought to England about
1750 by the third Duke of Argyll, and planted by him at Whitton, near
Hounslow. This tree, which has now disappeared, was measured by Loudon
before 1838 as 115 feet high.
[Illustration: WHITE POPLAR (_Populus alba_) IN JULY]
[Illustration: WHITE POPLAR (_Populus alba_) IN DECEMBER]