CHAPTER X.
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.