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.