THE CATKIN-BEARING TREES: ILLUSTRATED BY THE WALNUT, THE HICKORY, THE
WILLOW, THE POPLAR, THE ALDER, THE BIRCH, THE OAK, THE BEECH, THE
SWEET CHESTNUT, THE HAZEL, THE HORNBEAM, THE HOP HORNBEAM, THE PLANE
TREES, THE LIQUIDAMBAR, MYRICA, COMPTONIA, CASUARINA, AND _Garrya
elliptica_.
The plants contained in this chapter are placed by modern botanists in
six or seven different orders; but I have been induced to group them
together, both because they follow each other in regular succession,
and because there is a certain degree of general resemblance which
connects them together, and renders it easier to retain their names
when linked together by the association of ideas, than it would have
been if they had been each described separately.
The first order of catkin-bearing trees that I shall describe is
called Juglandaceæ, and it contains three genera, only two of which,
the Walnuts and the Hickories, are common in British gardens. The
second order, Salicaceæ, contains also two genera, the Willows and
the Poplars; the third, Betulaceæ, contains both the Alders and the
Birch trees; the fourth, Corylaceæ or Cupuliferæ, contains the Oak,
the Beech, the sweet Chestnut, the Hazel, and the Hornbeam; the fifth,
Platanaceæ, is generally considered to include two genera; viz.,
Platanus and Liquidambar, though this last is, by some botanists,
placed in a separate order called Balsamaceæ; and the sixth, Myricaceæ,
or the sweet Gale family. All the genera included in these orders,
with the exception of those belonging to Juglandaceæ, were formerly
comprised in one order, which was called Amentaceæ; from the word
Amentum, which signifies a catkin. The seventh and last order I have
mentioned in this chapter is called Garryaceæ, and consists of one
single genus, Garrya, only lately known in Europe. Of all these orders
the largest and most important is Cupuliferæ, as it includes, among
other valuable trees, the Oak and the Beech. All the plants mentioned
in this chapter have their male and female flowers distinct, many of
the genera having them on different plants; and the male flowers are
always in catkins, generally long and cylindrical, but sometimes round
and ball-shaped. The female flowers are sometimes in catkins also,
but sometimes they are produced singly or in pairs. The flowers of
both kinds are without petals, or with such as are inconspicuous; and
sometimes without even a calyx, but they are always furnished with
bracts, which grow so closely to the flower as almost to seem a part of
it. The ovaries are generally two-celled, but they rarely remain so,
as they become one-celled before the seed is ripe. The style is, in
most cases, very short, and the stigma generally two-lobed. The leaves
are always alternate, and generally simple, except in the case of the
Juglandaceæ. They are all hardy trees and shrubs.
JUGLANDACEÆ.—THE WALNUT TRIBE.
The genera belonging to this order have compound leaves, and the male
flowers in long cylindrical catkins; the male and female flowers being
on the same plant.
THE GENUS JUGLANS.
This genus consists of only three species: the common Walnut (_J.
regia_); the black Walnut (_J. nigra_); and the Butter-nut (_J.
cinerea_ or _cathartica_). The male and female flowers are distinct,
but on the same plant: the male flowers being produced in long,
solitary, cylindrical catkins, and the female ones in pairs, or in
shorter catkins. The leaves are pinnate, with the leaflets not always
opposite, which is very rarely the case in other plants. In _Juglans
regia_ (the common walnut), the male flowers are produced in a very
thick catkin, each flower consisting of a calyx divided into five or
six scale-like lobes, and generally from twelve to twenty stamens,
with very long anthers and very short filaments; there is also a very
curious bract to each, as shown in the magnified flower at _a_ in
_fig._ 77; in which the anthers are seen at _b_. The female flowers are
in pairs, as shown at _c_; and they consist of a calyx, _d_, enclosing
the ovary, and toothed in the upper part, and four small petals
encircling two large thick leafy-looking stigmas, _e_.
[Illustration: FIG. 77—WALNUT (_Juglans regia_).]
The fruit is a fleshy husk in one piece, formed of the dilated calyx;
it generally retains the stigmas till it has nearly attained its full
size, and when it becomes ripe it does not separate into valves, but
bursts irregularly. The nut, on the contrary, is in two distinct
valves, which may be easily separated from each other; and it is
imperfectly divided into cells by four half dissepiments. The germ of
the future plant is what children call the heart, and it is in the
upper part of the kernel, with the root end uppermost, so that when a
walnut is sown the sharp end should be placed downwards. The kernel is
four-lobed, and deeply wrinkled; and when the young plant begins to
grow, it divides into two cotyledons or seed-leaves, which drop off
when the true leaves are fully developed. The kernel is covered with
a thick skin, which is very astringent; and the nut is covered with a
membranaceous network of strong veins, which are generally found in a
withered state on opening the ripe husk, having left their impression
deeply imprinted on the outside of the shell of the walnut. The leaves
are impari-pinnate, consisting of four pairs of leaflets and a terminal
single one; the lower pair of leaflets is much the smallest, and the
other leaflets are frequently not opposite; and they are sometimes
unequal at the base. The main petiole is dilated at the point where
it joins the stem; and the leaves are placed alternately. The tree is
large and widely spreading; and the timber is of a close grain, and
takes a fine polish.
[Illustration: FIG. 78.—LEAF AND FRUIT OF THE BLACK WALNUT
(_Juglans nigra_).]
The Black Walnut (_J. nigra_) differs from the common kind, in the male
flowers being on a smaller and more slender catkin, and furnished with
a brown roundish bract at the back of the calyx. The female flowers are
also in a sort of catkin, and four or five together. The fruit (see
_a_ in _fig._ 78) is round, and the husk very thick at first, but
it gradually wastes away, when the seed is ripe, instead of opening.
The leaves have seven or more pairs of leaflets, which are generally
nearly opposite, and sometimes they are without the terminal single
leaflet, as shown at _b_. The shell of the nut is very hard, and the
dissepiments, which are also very hard, are generally perfect, and
divide the kernel into four parts. The nuts should be sown as soon as
possible after they are ripe, as they will not keep good above six
months. The tree grows above seventy feet high, and the wood is very
hard and black.
[Illustration: FIG. 79.—BUTTER-NUT
(_Juglans cathartica_).]
The Butter-nut (_J. cathartica_) resembles the Common Walnut in its
male catkins, except that they are produced upon the old wood instead
of being on the wood of the present year. The female flowers grow four
or five together in a short catkin, and they are distinguished by their
stigmas, which are rose-coloured. The fruit (_a_ in _fig._ 79) is
pear-shaped, ending in a rather long point; and the kernel of the nut
(_b_) resembles that of the Common Walnut, except in being more oily.
The leaves (_c_) are like those of the Black Walnut, except that the
leaflets are rather downy, and that there is a terminal one. The calyx
of the female flower is also covered with a viscid down, which remains
on the husk of the ripe fruit; and the shell of the nut is very hard
and very much furrowed. The tree is of much smaller size than that of
the Black Walnut, and it may be easily distinguished by the greyness
of the bark of its young shoots; it also comes into leaf earlier, and
the nuts are ripe about a fortnight sooner than the others. The wood is
light, of a reddish colour, and rather a coarse grain.
THE GENUS CARYA.
[Illustration: FIG. 80.—THICK-SHELL BARK HICKORY (_Carya lacinosa_).]
The genus Carya (the Hickory) consists of ten or twelve species, which
greatly resemble the Walnuts in their general appearance, but are
distinguished by the male catkins, instead of being solitary, being
produced in tufts or bunches, three or more on each peduncle. The
stigma is also frequently four-lobed, and the husk, when ripe, divides
into four equal valves, which in some of the species are very thick, as
in the Thick-shell bark Hickory (see _a_ in _fig._ 80). The nut (_b_)
is not valved, and it is either not furrowed, or very slightly so; but
it has four angles which are more or less distinct in the different
species: the shell and the dissepiments are both very hard, and the
latter, as in the Mocker nut, are sometimes entire, so as to render
it very difficult to extract the kernel. The leaves (_c_) resemble
those of the walnut; but they are generally of a thinner texture, and
somewhat downy, the down being disposed in little tufts, as may be seen
by a microscope. The trees vary much in size, but all of them have a
reticulated bark. The wood is of a coarse grain, and will not polish;
but it is very strong, and so remarkably tough that it is hardly
possible to break it.
There is only one other genus in the order Juglandaceæ, and that
consists of only a single species, _Pterocarya caucasica_. It has
pinnate leaves of nineteen leaflets each, placed as closely as possible
together; and the fruit, (that is, the husk,) is spread out on each
side into a thin membrane or wing. This plant is sometimes called
_Juglans fraxinifolia_.
SALICACEÆ.—THE WILLOW TRIBE.
The plants contained in this order have simple leaves, and the male
and female flowers on different plants, both in upright cylindrical
catkins.
THE GENUS SALIX.
The genus Salix (the Willow) contains perhaps more species than any
other, above two hundred and fifty having been named and described,
besides innumerable varieties. The plants included in the genus may,
however, be all divided into three kinds—viz. the true Willows, which
have thin green leaves, and which include all the tree species, most
of which have brittle branches; the Osiers, the leaves of which
resemble those of the Willows, but which are low shrubs with very tough
branches; and the Sallows, the leaves of which are thick and woolly or
shaggy. The Osiers and the true Willows are often confounded together;
particularly when the former take, as they sometimes do, a tree-like
character; but the Sallows are always perfectly distinct. The rods of
the Osiers are used in basket-making.
All the species of the genus have their male and female flowers on
different plants, both kinds of flowers being placed on short catkins
which are either erect or spreading sideways. The male flowers have
each from one to five or more stamens, with no petals or calyx, but as
a substitute a bract or scale, which is entire and hairy, and which has
one or more glands at its base. The female flower has a similar bract
or scale, and it is also without either petals or calyx; there are two
stigmas, each of which is sometimes two-lobed. The capsule has only one
cell, but many seeds which are covered with down or longish hairs, and
which are very conspicuous from the capsule opening naturally into two
valves when ripe. The leaves of the Osiers and Willows are generally
lanceolate, and serrated at the margin, and they are always furnished
with stipules; but the leaves of the Sallows are generally much
broader, and sometimes roundish; and they are always of a thick velvety
texture. Though the number of the stamens varies in the different
species, two are by far the most common.
[Illustration: FIG. 81.—THE WILLOW (_Salix_).]
_Fig._ 81 shows the female flower of _Salix fragilis_ at _a_, _b_ is
the honey gland, _c_ the stigma, which is divided into four equal
parts, and _d_ the bract or scale with its hairy fringe; _e_ is the
male flower with its two stamens, two glands, and hairy scale. This
species is a tall, bushy-headed tree, with the branches crossing
each other frequently, being set on obliquely; and it is called the
Crack Willow, from the young branches separating from the trunk in
spring with the slightest blow or jerk, their bases being as brittle
as glass. The leaves are of a deep green. The White Willow (_Salix
alba_) differs from the preceding species in the branches being widely
spreading and somewhat drooping, the old bark cracked into deep
fissures, and the foliage of a silvery grey, owing to the silky hairs
with which the leaves are more or less covered. The wood of the Tree
Willows is soft and white, and very elastic; it is therefore used for
cricket-bats, mallets, and other purposes where wood is wanted to
resist a hard blow. _S. vitellina_, the Golden Osier, is so called from
its golden-coloured bark; and _S. purpurea_, the Purple Willow, is so
called from the colour of its branches. This last species has only one
stamen; but as the anther is four-celled, it is probably two stamens
grown together. All the species that have only one stamen have a
four-celled anther, as for example the Rose Willow (_S. Helix_), which
has the female catkins red. _Salix caprea_, the great round-leaved
Sallow or Palm Willow, is perhaps the handsomest species, from the
great abundance and golden hue of its flowers.
THE GENUS POPULUS.
[Illustration: FIG. 82.—TREMBLING POPLAR OR ASPEN (_Populus tremula_).]
The genus Populus (the Poplar) is distinguished from Salix by the
bracts of the flowers being deeply cut instead of being entire; by
both the male and female flowers having a calyx; and by the male
flowers never having less than eight stamens. The leaf-buds are also
covered with numerous scales. _Fig._ 82, _a_, shows the stamens of
the Trembling Poplar or Aspen (_Populus tremula_) shrouded in their
cup-like calyx, and with their laciniated bract; _b_ shows the female
flower with its four stigmas and deeply-cut bract; and _c_, the pod
with its valves curling back, so as to show the downy covering of
the seeds. All these parts are magnified to show them distinctly, as
they are nearly the same in all the species. The following are the
distinctions between the principal species. In the White Poplar, or
Abele-tree (_P. alba_), the leaves are lobed, and covered with a white
down on the under side. In _P. canescens_, the Grey Poplar, the leaves
are also downy beneath; but they are roundish, and the female flower
has eight stigmas instead of four. The Aspen (_P. tremula_) has four
stigmas, with two leafy appendages at the base, which look like two
other stigmas; and the petioles of the leaves, which are very long,
are flattened, and so attached to the stem as to be twisted by the
weight of the leaf when acted upon by the wind, which gives them their
tremulous motion: these leaves are smooth on both sides. All these
species have spreading roots, and send up a great many suckers; and
their wood is used for butchers’ trays, pattens, bowls, milk-pails,
and various other purposes. _Populus nigra_, the Black English Poplar,
on the contrary, does not send up suckers, and its wood is of very
little use; it is, however, very ornamental from the large size and
great number of its male catkins, and the bracts of the flowers being
of a brownish red, which gives them, when fallen, the appearance
of the large brownish-red caterpillars of the Goat-moth. The Black
Italian Poplar (_P. monilifera_) is remarkable for the quickness of its
growth. The capsules of the female trees contain such a quantity of
down attached to the seeds, as to render it quite unpleasant to walk
under them when they are ripe. The Lombardy Poplar (_P. fastigiata_ or
_dilatata_) is remarkable for its upright and close habit of growth;
its leaves also are very peculiar in their shape, being broad at the
base and then tapering suddenly to a point. The seeds resemble those of
the Black Italian Poplar in the quantity of wool which they produce,
but luckily the female plants are extremely rare. There are many other
species, the most remarkable of which are the Carolina Poplar (_P.
angulata_), known by its square stem and very large leaves; the Balsam
Poplar, or Tacamahac tree (_P. balsamifera_), the buds of which are
covered with a resinous fragrant substance, and the leaves are of a
pale yellowish green, appearing very early in spring; and the Ontario
Poplar (_P. candicans_), which resembles the balsam Poplar, except in
its leaves, which are very large and whitish on the under surface, and
in the great rapidity of its growth, while that of the Balsam Poplar is
rather slow.
BETULACEÆ.—THE BIRCH TRIBE.
The plants included in this tribe have single leaves, which are
generally what is called feather-nerved; that is, the veins are marked
strongly and deeply from the mid rib to the margin. The flowers are
in cylindrical catkins, the male and female flowers being on the same
plant.
THE GENUS BETULA.
[Illustration: FIG. 83.—CATKINS OF THE BIRCH.]
[Illustration: FIG. 84.—THE BIRCH (_Betula_).]
The common Birch (_Betula alba_) is an exceedingly graceful tree. The
male catkins are produced singly, or two or three together. They are
long, slender, loose, and gracefully drooping; (see _fig._ 83;) and
each consists of a great number of flowers, pressed close together, and
growing round a rachis or stem, as shown in the catkin _a_ in _fig._
84, from which some of the flowers have been removed. The male flowers
have each ten or twelve stamens enclosed in three or more scales or
bracts, as shown in a reversed flower at _b_. The female flowers are
produced in dense catkins, which are much shorter than the others, and
always solitary; the flowers, which are arranged round a very slender
axis, are furnished with lobed scales, and _c_ is a scale with three
female flowers in its lobes, each having two long spreading stigmas
(_d_). A ripe capsule is shown at _e_, with its membranaceous wings,
and the cell _f_ open to show the seed. The ovary when young has two
cells and two ovules (as shown at _g_); but the division between the
cells wastes away as the seeds ripen, and one of the ovules proves
abortive. There are several species of Birch natives of America, some
of which have upright oval female catkins like those of the Alder, but
they are always distinguished by being solitary.
The bark of the Birch is remarkable for its tenacity, and for the great
length of time that it will resist decay. In America they make canoes
of the bark of _B. papyracea_; and in Lapland huts are thatched with
that of _B. alba_. The Birch is remarkably hardy; and it grows nearer
the limits of perpetual snow both on mountains and near the pole than
any other tree.
THE GENUS ALNUS.
The Common Alder (_Alnus glutinosa_), though so nearly allied to the
Birch botanically, differs widely in its habits; as it always grows
in low marshy situations, or near water, while the Birch prefers the
summits of the loftiest hills. In the Alder, the male catkins are long
and drooping, like those of the Birch; but they are generally produced
in clusters of three or more together. The male flowers are furnished
with three lobed bracts or scales, each containing three flowers,
each flower having a calyx of four scales united at the base, and
bearing four stamens. The female flowers are in close ovate catkins,
produced in clusters of four or five together, instead of being
cylindrical and solitary, as in the Birch; the scales of the catkins,
though three-lobed, are only two-flowered, and the flowers have two
long stigmas like those of the Birch. The ovary has two cells and two
ovules, but it only produces one seed. The ripe fruit is a nut without
wings, attached at the base to the scale of the cone-like catkin, the
scales of the catkin becoming rigid, and opening, like those of the
Scotch Pine, as the seed ripens. There are several species of Alder,
some of which bear considerable resemblance to the American species of
Birch; but they are easily distinguished by the female catkins of the
Birch being always solitary, while those of the Alder are produced in
clusters, and by the capsules of the Alder being without wings.
CUPULIFERÆ—THE CUP-BEARING TREES.
This order includes six genera of very important trees; all of which
have their ripe fruit shrouded in a cup-like involucre, which they
retain till ripe. The male and female flowers are on the same plant.
THE GENUS QUERCUS.
The fruit of all the species of Oak is an acorn, which is only partly
covered by a scaly involucre called the cup. The shape of the acorn,
and the height to which it is covered by the cup, differ in the
different species; but the general character of both is always the same.
[Illustration: FIG. 85.—THE OAK.]
[Illustration: FIG. 86.—GERMINATION OF THE ACORN.]
The male catkins of the common British Oak (_Quercus Robur
pedunculata_) are long and very few flowered; the flowers being small
and very far apart. The flowers themselves have six or eight stamens
and as many feathery bracts, which are united at the base. The female
flowers (_a_ in _fig._ 85) are produced on a long stalk at a distance
from each other, and each consists of an ovary closely covered with a
toothed calyx, as shown in the highly-magnified flower at (_c_), and
an involucre of several bracts or scales, (_d_); the style is short
and thick, and the stigma (_e_) is three-lobed. As the fruit ripens,
the style and stigma wither away, and the seed remains covered by
the adnate calyx (_b_), which has become hard and shining. There is
a circular mark or scar at the bottom of the acorn when taken out of
its cup, which is called the hilum; and when the acorn is planted,
this part should be kept upwards, as the foramen or part where the
germ lies is at the other end. When the acorn begins to germinate,
it opens at the foramen, cracking a little about half-way down, but
not dividing entirely (see _fig._ 86). The root (_a_) then begins to
protrude, and soon after the plumule, or young shoot (_b_), the leaves
of which gradually unfold themselves. A curious experiment may be tried
by suspending an acorn in a glass of water, or by placing it in one of
those glasses with a wide mouth and a narrow neck, used for nosegays;
when, if kept in a sitting-room, the acorn will gradually open, and the
root and leaves develop themselves; and thus may be watched the first
beginning of the monarch of the forest, the progress of which is so
strikingly depicted in the beautiful lines adapted by Cowper to the
hollow trunk of a gigantic oak in Yardley Chase near Castle Ashby:—
Thou wert a bauble once, a cup and ball
Which babes might play with; and the thievish jay,
Seeking her food, with ease might have purloin’d
The auburn nut that held thee, swallowing down
Thy yet close folded latitude of boughs,
And all thy embryo vastness, at a gulp.
Time made thee what thou wert—King of the Woods!
And time hath made thee what thou art—a cave
For owls to roost in! Once thy spreading boughs
O’erhung the champaign, and the numerous flock
That grazed it, stood beneath that ample cope
Uncrowded, yet safe shelter’d from the storm.
Embowell’d now, and of thy ancient self
Possessing nought but the scoop’d rind, that seems
A huge throat calling to the clouds for drink,
Which it would give in rivulets to thy roots;
Thou temptest none, but rather much forbidd’st
The feller’s toil, which thou wouldst ill requite.
Yet is thy root sincere, sound as a rock:
A quarry of stout spurs and knotted fangs,
Which, crook’d into a thousand whimsies, clasp
The stubborn soil, and hold thee still erect.
Thine arms have left thee—winds have rent them off
Long since; and rovers of the forest wild
With bow and shaft have burnt them. Some have left
A splinter’d stump, bleach’d to a snowy white;
And some, memorial none where once they grew.
Yet life still lingers in thee, and puts forth
Proof not contemptible of what she can,
Even when death predominates. The spring
Finds thee not less alive to her sweet form,
Than yonder upstarts of the neighbouring wood,
So much thy juniors, who their birth received
Half a millennium since the date of thine.
The leaves of the common Oak are deeply sinuated, and without
footstalks, but those of _Quercus Robur sessiliflora_, another British
Oak, are upon short footstalks, though the acorns are sessile. This
last species predominated in the oak forest which formerly surrounded
London; and many examples are still to be found at Lord Mansfield’s
beautiful seat at Hampstead, the name of which, Ken wood, alludes to
them, Ken being Saxon for an acorn. The wood of this tree was also used
for the roof of Westminster Hall, and many other ancient buildings
which till lately were supposed to be of Chestnut. Oak wood may always
easily be tested by wetting a knife and then cutting it, when the
astringent property in the Oak will turn the knife black, a result that
will not take place with Chestnut.
There are nearly fifty species of Oaks which may be obtained in the
British nurseries; the most remarkable of which are the Cork tree
(_Quercus Suber_), the cork being the bark; the Evergreen Oak (_Q.
Ilex_); the American Oaks, particularly the scarlet Oaks (_Q. coccinea_
and _Q. rubra_), the Live Oak (_Q. virens_), and the Willow Oak, with
long narrow entire leaves
(_Q. Phellos_); and the Turkey, Fulham, and Lucombe Oaks (_Q. Cerris_
and its varieties). All Oak trees are very liable to be attacked by a
species of gnat, and which produces excrescences on the branches. The
oak apples of the British Oak, and the galls of _Quercus infectoria_,
which are used in making ink, are of this nature. The Kermes, an
excrescence found on _Quercus coccifera_, is the work of a kind of
Coccus, similar to that which produces the cochineal on the Opuntia.
The timber of all the European Oaks is remarkably durable; but that
of nearly all the American Oaks, except _Quercus virens_, is coarse
grained, and so porous that it cannot be used for wine casks. The cork
trees are generally grown in Spain; and as the cork when taken off the
tree, curves round, it is laid upon the ground and kept flat with heavy
stones; while a fire is made upon it with the branches, so as to heat
it through, after which it remains flat when the stones are removed.
THE GENUS FAGUS.
[Illustration: FIG. 87.—THE BEECH (_Fagus_).]
The Beech (_Fagus sylvatica_) bears very little resemblance to the
Oak. The male flowers are in globular catkins (see _a_ in _fig._ 87),
each flower consisting of a bell-shaped calyx (_b_), cleft into five
or six teeth, and containing eight or ten stamens, which project
beyond it. The female flowers also grow in globular heads (_c_) two
or three together, surrounded by a great number of linear bracts,
which gradually grow together, and form a four-lobed involucre shown
open at _d_. In the centre of this involucre are two or more female
flowers, each surrounded by a hairy calyx, cut into teeth at the tip
(_e_). Each flower has three styles (_f_); and the ovary, which is
sharply angular, has three cells, with two ovules in each. As the fruit
swells, the linear bracts diminish, till at last they have only the
appearance of small spines on the involucre (_g_), which opens when
ripe into four valves (_h_), and contains two or three angular nuts
(_i_), which are called the mast. The leaves of the Beech are of thin
and delicate texture, and they are strongly feather-nerved. The tree
is large and very handsome, and it is easily known, even in winter, by
the smooth shining white bark of the main trunk. There are only two
species of Fagus common in British gardens, and these are the common
Beech (_Fagus sylvatica_) which has numerous varieties, including one
with dark reddish purple leaves, generally called the Purple Beech;
and the American Beech (_F. ferruginea_), the leaves of which are
copper-coloured.
There are, however, two species from Terra del Fuego, which have
been introduced, but they are at present rare. One of these (_F.
betuloides_) is called the Myrtle tree in Van Dieman’s Land, where it
is also found wild, and it is remarkable for producing a fungus on its
trunk, which, when cut in slices and cooked, is said to be very good to
eat.
THE GENUS CASTANEA.
[Illustration: FIG. 88.—CHESTNUT (_Castanea vesca_).]
[Illustration: FIG. 89.—FRUIT OF THE SWEET CHESTNUT.]
This is a very small genus, only containing two or three species, of
which only one, the Sweet Chestnut (_Castanea vesca_) is common in
England. This plant was included by Linnæus in the genus Fagus, but it
appears very distinct. The male flowers are produced round a central
axis, but so far apart as hardly to be like a catkin (see _a_ in
_fig._ 88). These flowers in the bud look like little knobs, but when
they open the stamens burst out, as shown at _b_. Each flower has a
large and a small bract, and from ten to fifteen stamens. The female
flowers are disposed in a tuft as shown at _c_, surrounded by a number
of bracts and scales, which afterwards grow together and form a spiny
involucre (see _fig._ 89 _a_,) which forms the husk of the ripe nuts
(_b_), and opens into four valves as shown at _c_. Each female flower
has a closely-fitting calyx, toothed at the tip, which afterwards
becomes the hard brown skin that envelops the kernel of the ripe nut;
and each flower is furnished with six styles, having as many cells
with two ovules in each, though generally all the cells unite into one,
and most of the ovules wither before the fruit ripens. There are three
female flowers in each involucre, which lie nestling together like
birds in a nest. When ripe the involucre or husk opens naturally into
four valves (as shown in _fig._ 89), and drops the one or two Chestnuts
which it contains. Each nut, when ripe, is enveloped in a brittle
shining skin formed of the metamorphosed calyx, and consists of only
one cell, in which are one, two, or at most three kernels, which are
the seeds.
THE GENUS CORYLUS.
[Illustration: FIG. 90.—THE HAZEL (_Corylus Avellana_.)]
[Illustration: FIG. 91.—MALE FLOWER OF THE HAZEL.]
The Hazel Nut (_Corylus Avellana_) has the male and female flowers on
the same tree; the male being in long catkins and the female ones in
little oval buds, something like those of the Oak, (see _a_ in _fig._
90,) which are so small that they would hardly be seen on the tree, if
it were not for their bright red stigmas. The male flowers (_fig._ 91)
have each three bracts, one behind the two others, to the inner ones
of which are attached eight stamens. As the buds containing the female
flowers expand, two or three small leaves make their appearance between
the scales (_b_ in _fig._ 90), so that gradually the bud becomes a
little branch, bearing the female flowers at its tip. Each flower has
two long stigmas, and the ovary is enclosed in a closely-fitting calyx
(_c_) toothed at the upper part, the whole being enveloped in a deeply
cut involucre (_d_), which afterwards becomes the husk of the ripe
nut. This involucre is not closed, as in Fagus and Castanea, but it
is open at top; the nut, as in all cupuliferæ, adhering to it, when
young, by the hilum or scar visible at its base. There are about seven
species of Corylus, of which the most remarkable is the Constantinople
Nut (_Corylus Colurna_.) The Filbert is only a variety of _Corylus
Avellana_.
THE GENUS CARPINUS.
[Illustration: FIG. 92.—FRUIT OF THE HORNBEAM.]
Some botanists include this genus and that of Ostrya in the order
Betulaceæ, instead of placing them in Cupuliferæ, as the nut of the
Hornbeam is not surrounded by a cup or husk, but by a leaf-like
involucre as shown in _fig._ 92, at _a_, _b_ being the nut. Both the
male and the female flowers are produced in long catkins, which have an
exceedingly light and elegant appearance on the tree. The male flowers
consist each of one bract, with twelve or more stamens attached to its
base; and the female flowers have each two very long stigmas, and a
ribbed calyx, which adheres to the ripe nut and assumes the appearance
of a hard brown skin. The leaves are feather-nerved and persistent,
like those of the Beech, frequently remaining on the tree, though in a
withered state, till spring.
The nut appears ribbed when ripe, from the remains of the metamorphosed
calyx, and it contains only one seed; though, as in the other allied
genera, the ovary had two cells, with an ovule in each.
THE GENUS OSTRYA.
The Hop Hornbeam (_Ostrya vulgaris_) was included in the genus Carpinus
by Linnæus; and indeed the general construction of the flowers is the
same. The male catkins are, however, very much longer, and the female
catkins much shorter, and closely resembling those of the Hop.
THE ORDER PLATANACEÆ.
This order formerly included the Plane trees and the Liquidambar; but
many botanists now put the latter tree in a separate order, which they
call Balsamaceæ.
THE GENUS PLATANUS.
In the Oriental Plane (_Platanus orientalis_) the male and female
flowers are both in globular catkins. The male flowers are composed
of very small, but rather fleshy bracts, which remain on after the
stamens fall; and the female flowers are each furnished with bracts,
and have two long stigmas. Both kinds of flowers are so small as not to
be seen without a microscope. The fruit is covered with fine hair. The
globular catkins retain the bracts, and these remain on after the seed
has fallen, giving the tree a very singular appearance even in winter.
The Occidental Plane (_P. occidentalis_) differs principally from the
preceding species in the leaves being more downy beneath; the buds are
also so downy that the tree in America is called the Cotton-tree. Both
kinds are remarkable for the manner in which the bark becomes detached
from the main trunk and peels off.
THE GENUS LIQUIDAMBAR.
The common Liquidambar (_L. styraciflua_) is remarkable for the
beautiful crimson which its maple-like leaves take in autumn. The male
flowers are on an upright catkin, and the female ones in a globular
one, like the Planes. When the fruit is ripe, the numerous capsules
that surround the globular catkin burst, and the seeds, which are
winged, are scattered by the wind.
THE ORDER MYRICACEÆ.
The principal genera are Myrica, the Sweet Gale; Comptonia, a curious
shrub with fernlike leaves; and Casuarineæ, a New Holland tree without
leaves, but with jointed leaf-like stems.
THE GENUS MYRICA.
The male flowers are produced in rather long erect catkins, each having
only one scale, and four stamens. The female catkins are short, and
each flower has three scales or bracts; the ovary has two long stigmas,
and the fruit is a drupe, the scales becoming fleshy when ripe. The
bracts and leaves are covered with glands filled with aromatic oil; and
in _M. cerifera_, the fruit is covered with a waxy secretion, which is
used as wax.
THE ORDER GARRYACEÆ.
This order consists of only one genus, Garrya.
THE GENUS GARRYA.
_Garrya elliptica_ is an evergreen shrub remarkable for its long and
graceful male catkins, the flowers of which consist of four stamens
within a four-cleft calyx, enclosed within bracts united at the base.
The female flowers are on a different plant, and the fruit is a berry
not opening naturally.