Production—In the south-west of India, the plant, or Pepper Vine as it is called, grows on the sides of the narrow valleys where the soil is rich and moist, producing lofty trees by which a constant, favourable coolness is maintained. In such places the pepper-vine runs along the ground and propagates itself by striking out roots into the soil. The natives tie up the end of the vines lying on the ground to the nearest tree, on the bark of which the stems put out roots so far as they have been tied, the shoots above that hanging down. The plant is capable of growing to a height of 20 or 30 feet, but for the sake of convenience it is usually kept low, and is often trained on poles. In places where no vines occur naturally, the plant is propagated by planting slips near the roots of the trees on which it is to climb.
The pepper plants if grown on a rich soil begin to bear even in the first year, and continue to increase in productiveness till about the fifth, when they yield 8 to 10 lb. of berries per plant, which is about the average produce up to the age of 15 to 20 years; after this they begin to decline.
When one or two berries at the base of the spike begin to turn red, the whole spike is pinched off. Next day the berries are rubbed off with the hands and picked clean; then dried for three days on mats, or on smooth hard ground, or on bamboo baskets near a gentle fire.
In Malabar the pepper-vine flowers in May and June, and the fruits become fit for gathering at the commencement of the following year.[2162]
The largest quantities of pepper are produced in the island of Rhio, near Singapore, in Djohor (in the south-eastern coast of the Malayan Peninsula), and in Penang. The latter island affords on an average about one-half of the total crop.
Description—The small, round, berry-like fruits grow somewhat loosely to the number of 20 to 30, on a common pendulous fruit-stalk. They are at first green, then become red, and if allowed to ripen, yellow; but they are gathered before complete maturity, and by drying in that state turn blackish grey or brown. If left until quite ripe they lose some of their pungency, and gradually fall off.
The berries after drying are spherical, about ⅕ inch in diameter, wrinkled on the surface, indistinctly pointed below by the remains of the very short pedicel, and crowned still more indistinctly by the 3-or 4-lobed stigma. The thin pericarp tightly encloses a single seed, the embryo of which in consequence of premature gathering is undeveloped, and merely replaced by a cavity situated below the apex. The seed itself contains within the thin red-brown testa a shining albumen, grey and horny without, and mealy within. The pungent taste and peculiar smell of pepper are familiar to all.
Microscopic Structure—The transverse section of a grain of black pepper exhibits a soft yellowish epidermis, covering the outer pericarp. This is formed of a closely-packed yellow layer of large, mostly radially arranged, thick-walled cells, each containing in its small cavity a mass of dark brown resin. The middle layer of the pericarp consists of soft, tangentially-extended parenchyme, containing an abundance of extremely small starch granules and drops of oil. The shrinking of this loose middle layer is the chief cause of the deep wrinkles on the surface of the berry. The next inner layer of the pericarp exhibits towards its circumference tangentially-arranged, soft parenchyme, the cells of which possess either spiral striation or spiral fibres, but towards the interior loose parenchyme, free from starch, and containing very large oil-cells.
The testa is formed in the first place of a row of small yellow thick-walled cells. Next to them follows the true testa, as a dense, dark brown layer of lignified cells, the individual outlines of which are undistinguishable.
The albumen of the seeds consists of angular, radially-arranged, large-celled parenchyme. Most of its cells are colourless and loaded with starch; others contain a soft yellow amorphous mass. If thin slices are kept under glycerin for some time, these masses are slowly transformed into needle-shaped crystals of piperin.