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.
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 Fig.72.—Nettle (Urtica dioica). 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.
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.
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 Fig.74.—Hemp. (Cannabis sativa.) 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 ex cited 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.” Fig.75.—Upas tree. (Humboldt, as quoted in the Botanical Magazine, vol. 66, t. 3724.)
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.
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.
