THE ORDER URTICACEÆ: ILLUSTRATED BY THE COMMON NETTLE; THE HOP; THE
HEMP; THE PELLITORY OF THE WALL; THE BREAD-FRUIT TREE; THE JACK-TREE;
THE COW-TREE OR PALO DE VACCA; THE UPAS OR POISON-TREE OF JAVA; THE
MULBERRY; THE PAPER MULBERRY; THE OSAGE ORANGE, OR MACLURA; THE
COMMON FIG; FICUS SYCAMORUS; THE BANYAN TREE; THE INDIAN-RUBBER TREE;
AND FICUS RELIGIOSA.
This very large order is divided into two distinct tribes, which many
botanists make separate orders; the one embracing the herbaceous
species with watery juice, and the other the ligneous species, all of
which have their juice milky. The botanical construction of the flowers
is, however, strikingly alike in all, from the nettle and the humble
pellitory of the wall, to the fig and bread-fruit tree. In all the
genera, the male and female flowers are distinct, that is to say, some
of the flowers have only stamens, and the others only a pistil; the
latter, of course, being the only ones that produce seed. None of the
flowers have any corolla; and in all the male flowers, the stamens,
which are erect at first, spring back with elasticity to discharge
their pollen, and afterwards remain extended. The seeds of all are
enclosed in nuts: though the eatable part varies, being in some the
dilated receptacle, as in the Bread-fruit and the Fig, and in others
the metamorphosed calyx, as in the Mulberry. Many of the genera have
one or two species which produce eatable fruit, though the fruit of the
other species of the same genus is unwholesome; an anomaly rarely to
be met with in any other order except Solanaceæ; and though the milky
juice of most of the plants is poisonous, it affords in one species,
the Cow-tree, wholesome food.
TRIBE I.—URTICACEÆ.
All the plants contained in this tribe agree with the common Nettle
in yielding a watery juice when broken; in their flowers having no
corolla; in the male and female flowers being distinct; in the stamens
being first erect, but springing back when they discharge their pollen,
and remaining extended; and in their fruit being a nut. Most of them
also agree in having rough leaves and angular stalks, the fibres of
which are so tenacious as to be capable of being spun.
[Illustration: FIG. 72.—NETTLE (_Urtica dioica_).]
The common Nettle (_Urtica dioica_) is the type of this division;
and we are so accustomed to consider it a noxious weed, that few
persons are aware of the elegance of its flowers, which are disposed
in drooping panicles. The male flowers have their calyx divided into
four sepals; and they have four stamens, the anthers of which open
with elasticity, and when they spring back, the pollen, which is very
abundant, is discharged with such force that it may be seen on a fine
day in summer rising like a mist or light cloud over the plants. The
stamens, after they have discharged their pollen, lie extended and
curved back over the segments of the calyx, as shown at _a_ in _fig._
72. The female flowers have only two segments to the calyx. They have
no style, and the stigma, when highly magnified, will be found divided
into numerous segments, as shown at _b_; the seed-vessel is a nut,
which has a shell and kernel, the latter being the seed. The leaves are
simple, cordate, opposite to each other, and furnished with stipules.
They are rough on the surface, and covered with glandular hairs or
stings. These hairs are hollow, with a cell at the base filled with a
peculiarly acrid liquid, and tapering upwards so as to form a narrow
tube, ending in a sharp point. When the point of the sting enters the
skin, the pressure compresses the cell at its base, and the liquid it
contains is forced up the tube and injected into the wound. The stem
is quadrangular, and its fibres are so tough, that when separated from
the pulp by maceration, they may be spun into yarn. The young shoots
when boiled are very good to eat. The Roman Nettle (_U. pilulifera_)
differs from the common kind in having the male flowers in loose
panicles, and the female ones in compact pill-like heads, whence the
specific name. The sting of this nettle is worse than that of the
common kind.
[Illustration: FIG. 73.—HOP (_Humulus Lupulus_).]
The Hop (_Humulus Lupulus_) is a very interesting plant to a botanist,
from the peculiarity of its flowers. The male and female ones are
distinct, and generally on different plants. The male flowers are
produced in loose panicles; the calyx (_fig._ 73, _a_) consists of five
sepals, in the centre of which are five stamens, standing at first
erect, but springing back with elasticity, when they discharge their
pollen, and remaining extended as shown at _b_. The anthers open by
pores at the extremity of the cells, as in Ericaceæ. The female flowers
are produced in close heads (_c_). They have neither calyx nor corolla,
but the ovary of each is protected by a membranous scale. Each ovary
has two styles, though it produces only a single seed. As the fruit
ripens the styles disappear, and the scales enlarge, so as to give the
head of female flowers the form of a strobile or cone (_d_), the ripe
fruit or nut being placed at the base of each scale, as shown at _e_.
The surface of the scales is studded over with roundish glands, which
are filled with a substance resembling pollen, called lupuline, which
they give out on pressure, as shown at _f_; and this substance consists
of a number of cells filled with volatile oil, which occasion the
fragrance of the hop, and contain the bitter and astringent principles
which make the hop so useful in compounding malt liquor. The lupuline
is also somewhat narcotic; but though the fragrance of hops is said
to produce sleep when inhaled in small quantities, an excess of it
produces headache and vertigo, especially in nervous persons. The
leaves are opposite, and three or five lobed; they are serrated on
the edges, and rough on the surface. The stems are angular, covered
with small prickles, and twining from left to right. The fibres of the
stem when separated by soaking in water, are found to possess the same
kind of tenacity as those of the Nettle and the Hemp, and may be made
into cloth. The young shoots when boiled, are very good to eat as a
substitute for asparagus. The leaves are furnished with stipules, and
the flowers spring from the axils of the leaves.
[Illustration: FIG. 74.—HEMP. (_Cannabis sativa._)]
The Hemp (_Cannabis sativa_), is an annual. The male and female flowers
are on different plants as in the Hop and the Nettle. The male flowers
are produced in panicles, and the female ones in heads separated by
bracts, as shown in a magnified female flower at _a_ in _fig._ 74. The
ripe fruit or nut is enveloped in a scale as shown at _b_; and _c_ is a
highly magnified section of the nut. The male flower has five stamens,
and a calyx of five sepals. The leaves are opposite or alternate, and
digitate, that is cut into five long segments like fingers, though the
upper leaves have only three segments. They are serrated on the margin,
and rough on the surface. The fibres of the stem, when separated from
the pulpy part by maceration, are manufactured into cordage; and the
seeds are mucilaginous, and are used for feeding birds. The smell of
hemp when growing, produces the same effects as that of hops in excess;
and in hot countries it is followed by a kind of stupor, like that
which is the effect of opium.
The Pellitory of the wall (_Parietaria officinalis_), has the male and
female flowers on the same plant. The male flowers have four stamens,
which spring back in the same manner as those of the nettle; and the
female flowers have the same kind of stigma.
TRIBE II.—ARTOCARPÆ.
The plants included in this division differ so widely in their general
appearance from those of the former tribe, that it is necessary to be a
botanist to perceive the resemblance between them. When, however, they
are botanically examined, they will be found to agree in almost every
respect, except in their juice being milky and glutinous instead of
watery. The tribe takes its name from the Bread-fruit tree (_Artocarpus
incisa_). In this plant, the male flowers are densely crowded round
a spongy receptacle, so as to form a long, somewhat club-shaped cat
kin. Taken singly, each male flower consists of a calyx divided into
two sepals, and containing a single stamen, with a two-celled anther,
and a very broad filament. The female flowers are placed round a
globular receptacle, also of a spongy consistency; and each consists
of an undivided calyx, hollow at the base to contain the seed, and
terminating in two styles. The styles wither as the seeds gradually
ripen, but the peaks of the female flowers remain, and render the
surface of the fruit rough. The fruit itself is the spongy receptacle,
which gradually dilates and becomes more pulpy, till it attains a very
large size. The greater part of the ovules prove abortive, but those
that ripen retain their calyx, though they remain embedded in the
pulp. The proportion of ripe seeds is very small compared to the size
of the eatable part of the bread-fruit; frequently only four or six
seeds are found in a globe eight inches in diameter; and many fruits
produce no seeds at all. One variety, in particular, is always without
seeds. The fruit, when used, is generally put into an oven or before
a fire, and when the rind turns black, it is scraped off, and the
pulp is found to resemble the crumb of new bread. The seedless fruits
are considered the best to eat, and they are known by the smoothness
of their outer surface. It adds to the interest excited by this
singular tree, to recollect that the Bounty, rendered so celebrated
by the mutiny of Christian, was sent out, under Captain Bligh, to
convey a number of plants of this tree from Otaheite to the British
settlements in the West Indies; and that there actually were seven
hundred and seventy-four plants on board, at the very time the mutiny
broke out. The leaves of the Bread-fruit tree are very large, being
sometimes two or even three feet long, and a foot and a half broad;
they are leathery, and are cut into from three to nine deep lobes.
Their colour is a deep green, with yellowish veins. The petioles are
short and thick, and there are large stipules which wither and fall off
before the leaves. The whole plant abounds in milky juice, which flows
abundantly when the leaves or branches are wounded or broken.
The Jack tree (_Artocarpus integrifolia_), bears fruit of an oblong
form often seventy or eighty pounds in weight, the pulp of which is
seldom eaten; but the seeds, which are abundant, are considered very
good, and are said when roasted to have the flavour of sweet chestnuts.
The leaves are very thick and leathery, and much smaller than those
of the Bread-fruit, being seldom more than six or eight inches long.
They are also generally entire, but this is by no means a constant
character, notwithstanding the specific name, as those near the root
are sometimes found nearly as deeply lobed as those of _A. incisa_. The
Jack tree is a native of the East Indies, particularly of the Molucca
Isles, Amboyna, and Ceylon, and it also seems naturalised in the West
Indies, particularly in the Island of St. Vincent. The wood resembles
that of mahogany.
The Cow tree, or Palo de Vacca (_Galactodendron utile_), appears
nearly allied to the Bread-fruit tree, though its flowers are unknown.
The nut, however, which is covered with a husk apparently composed
of the hardened calyx, resembles those of the other plants belonging
to the Urticaceæ, and the bark when wounded gives out abundance of
milk, which is good to drink. Humboldt in his _Relation Historique_,
describes this tree as “growing on the sides of the rocks, its thick
roots scarcely penetrating the stony soil, and unmoistened during many
months of the year by a drop of rain or dew. But dry and dead as the
branches appear,” Humboldt continues, “if you pierce the trunk, a sweet
and nutritive milk flows forth, which is in the greatest profusion
at day-break. At this time the blacks, and other natives of the
neighbourhood, hasten from all quarters, furnished with large jugs to
catch the milk, which thickens and turns yellow on the surface. Some
drink it on the spot, others carry it home to their children; and you
might fancy you saw the family of a cowherd gathering around him, and
receiving from him the produce of his kine.” (_Humboldt, as quoted in
the Botanical Magazine_, vol. 66, t. 3724.)
[Illustration: FIG. 75.—UPAS TREE.]
The Upas, or Poison tree of Java (_Antiaris toxicaria_), about which so
many fabulous stories have been told, belongs to this tribe. The male
flowers are gathered together in small heads on a fleshy receptacle,
(see _fig._ 75 _a_;) and each consists of a calyx of four sepals (_b_),
bending over four stamens, with long anthers and very short filaments.
The female flowers have an undivided fleshy calyx with two styles,
and this fleshy covering forms the pericardium of the fruit, which
is a drupe. When ripe, the fruit represents a moderately sized plum,
inclosing the nut, or stone, which contains the kernel or seed. The
poison lies in the milky sap.
[Illustration: FIG. 76.—MULBERRY.]
The common black Mulberry (_Morus nigra_) has the general features of
the order. The male flowers grow together in a dense spike, as shown in
_fig._ 76 at _a_, and each flower consists of a calyx of four sepals,
and four stamens, which spring back and remain extended after they have
discharged their pollen (_b_). The female flowers also grow closely
together, in dense spikes, round a slender receptacle; each having
two elongated fringed stigmas (_c_), and a calyx of four sepals, and
being inclosed in an involucre, as shown at _d_. As the seeds ripen,
each female flower becomes a drupe, consisting of a fleshy and juicy
pericardium formed from the calyx, and the nut; and these drupes being
pressed closely together by the position of the female flowers, the
whole adhere together and form the fruit we call the mulberry. The
involucre withers when the calyx becomes juicy; but the remains of it
and of the style are often seen on the ripe fruit, as shown at _e_.
The receptacle also remains as a sort of core, which is thrown away
when the fruit is eaten, though it does not part from it so freely as
in the raspberry; and the little nuts, or seeds as they are called,
are found in the centre of each juicy globule. The leaves are simple,
entire, and rough on the surface.
The white Mulberry (_Morus alba_) differs from the common kind in the
fruit not being eatable; as the calyxes of the female flowers never
become juicy. The leaves are, however, much smoother and of finer
texture than those of the black mulberry, and they are principally used
for feeding silkworms, for which those of the black mulberry are not so
good.
The red Mulberry (_M. rubra_) is an American species, with leaves
too rough to be good for silkworms, and very indifferent fruit. The
Constantinople and Tartarian Mulberries are supposed to be only
varieties of _M. alba_, though their fruit is good to eat, and the
latter has lobed leaves.
The Paper Mulberry (_Broussonetia papyrifera_) has the male and female
flowers on different plants. The male flowers are produced in pendulous
catkins, and the calyx has a short tube before it divides into four
segments; each flower is also furnished with a bract, but in other
respects their construction is the same as that of the other flowers of
the order. The female flowers have also a tubular calyx, and they are
disposed in globular heads on rather long peduncles; but they differ
from those of the other genera in having only a single stigma, and
in the ovary being inclosed in an integument within the calyx, which
becomes juicy as the seeds ripen, and not the calyx itself. The leaves
are very irregularly lobed, and hairy; and the liber or inner bark is
used for making what is called Indian paper.
The Osage Orange (_Maclura aurantiaca_), has the male and female
flowers on different plants, the male being borne in short close
panicles of ten or twelve flowers each, and not differing in
construction from those of the other genera. The female flowers are
borne on a large globular receptacle, like that of the bread-fruit;
and they resemble those of that plant in construction, except that
they are pitcher-shaped instead of being angular, and that they have
only one stigma instead of two. The receptacle also never becomes soft
and pulpy like that of the bread-fruit, but remains hard and stringy
and unfit to eat. The leaves are smooth and of delicate texture, and
as they abound in glutinous milk, they have been found very suitable
for silkworms. The wood is of a beautiful glossy texture, and very
fine and close-grained. The tree is found wild in the country of the
Osage Indians, near the Mississippi, and from the rough surface of its
fruit, and its golden-yellow colour, it has received the name of the
Osage Orange.
The common Fig (_Ficus Carica_) has its male and female flowers on the
same plant, and often within the same receptacle. The receptacle in
this plant instead of being surrounded by the flowers, incloses them,
and is, in fact, the fruit we call a fig. This receptacle is sometimes
roundish, but more generally pear-shaped; and it is not quite closed,
but has a little opening or eye at the upper end, which is fitted in
with several very small scales. The stalk of the fig is articulated on
the branch. The male flowers are generally in the upper part of the
fig, and they consist of a half tubular calyx, with a limb divided
into three segments, and three stamens. The female flowers have each
a calyx of five sepals, and a single style with two stigmas; and
they are succeeded by the seeds, or nuts as they are called, as each
contains a kernel which is the true seed. The leaves are very small
when they first expand, but they gradually increase in size, till
they become very large. They are generally lobed, and their petioles
are articulated. The figs are produced in the axils of the leaves. It
may be observed here, that Du Hamel mentions that the receptacle is
not closed in all the varieties of the fig, but that in some it opens
naturally, when the seeds are ripe, dividing at the orifice into four
equal parts, like the valves of a capsule; and even when this is not
the case, the figs, when the receptacle becomes pulpy and soft from
ripeness, crack and burst at the sides, so as to allow of the escape of
the seeds.
As the fig is not fit to eat till the seeds are ripe, various
expedients have been devised to transmit the pollen from the male
flowers which lie near the opening or eye, to the female flowers which
lie nearer the stalk. In Italy this is called caprification, and is
done by insects; but in the neighbourhood of Paris, a very small
quantity of oil is dropped on the eye of the fruit as soon as it has
nearly attained its full size.
There are several species of Ficus, though none of them will bear
the open air in England except the common kind; and only two produce
eatable fruit; viz., _F. Carica_, and _F. Sycamorus_,—the Sycamore tree
of Holy Writ, which produces its small roundish fruit in clusters on
the trunk and old branches, and not on the young wood, as is always the
case with the common fig.
The other most remarkable species are the Banyan tree (_F. indica_),
the figs of which grow in pairs, and are about the size and colour of
a cherry; and the branches of which send down roots, which soon become
equal in size to the parent trunk, so that one tree soon becomes like
a small forest; the Indian-rubber tree (_F. elastica_), the milky
juice of which hardens into Caoutchouc, though this substance is also
produced by other trees, particularly by the Brazilian tree _Siphonia
elastica_; and the Pippul tree (_F. religiosa_). The leaves of this
last tree are used in India for feeding silkworms, and it is said that
this is one cause of the strong and wiry nature of the Indian silk;
and the insect (_Coccus ficus_) feeds upon it and _F. elastica_, which
produces the substance called lac, of which sealing-wax is made. This
species takes its specific name of _religiosa_, from the legend that
the Hindoo god Vishnoo was born under its branches.