The rhizome sometimes grows to a great size; often a single root will weigh one pound. It is a great impovisher of land and the same ground should not be used more than two consecutive years, and it is better to use it but one year. The yield is 4,000 pounds and upwards to an acre, each plant producing about eight tubers, and eight to ten times more in weight than the amount planted.
The ginger of commerce varies in form from single joints an inch or less in length to flattish, irregularly branched pieces of several joints from three to four inches long. Each branch has a depression at its summit, showing the former attachment of a leafy stem. The color in its natural state is a pale buff. It has a somewhat rough or fibrous appearance, breaking with a short, mealy fracture, and presenting on the surface of the broken parts numerous short, bristly fibers. When young, it has a light color, internally soft, and changing to greenish. As it grows older it becomes grey outside and reddish internally. When ready for digging the texture becomes fibrous and firm and heavy, and when dried it is covered with wrinkled striated brown integuments which give it a crude appearance, which is less developed on the flat surface and, internally, it is less bright and delicate than ginger from which the cuticle part has been removed. The best pieces of ginger root are collected at the harvest and thrown into heaps and covered with cow manure to keep the roots from drying for the next planting.
The scraped ginger, or marrow, has a pale hue and breaks readily and moderately short, the younger and terminal portions appearing pale yellow, being soft and starchy, while the longer transverse sections of the more perfect and outer parts are hard, flinty, and resinous, surrounding a farinaceous center which has a speckled appearance from the cut extremities of the fibers and ducts. The external layer of coated ginger is separated, about one millimeter broad, by a fine line from the whitish mealy interior portion, through the tissue of which numerous vascular bundles and resin cells are irregularly scattered. The external tissue consists of loose outer layer and an inner composed of tubular cells. These are followed by peculiar short parenchymatous cells, the walls of which are sinuous on a transverse section, and partially thickened, imparting a horny appearance. This delicate, felted tissue forms the striated surface of scraped ginger and is the principal seat of the resin and volatile oil, which here fill large spaces, the principal constituents being of the parenchymatous cells loaded with starch and resin. The volatile oil gives ginger its odor; the resin, pungency. The starch granules are irregularly spherical in form, attaining at the utmost forty millimeters in diameter. Certain varieties of ginger, owing to the starch having been rendered gelatinous by scalding, are throughout horny and translucent. The circle of vascular bundles which separates the outer layers and the central portion is narrow and has the structure of the corresponding circle or nucleus sheath of tumeric. (See illustrations 12, 13, 14, Chap. III; illustration 12 shows ginger adulterated; 13 and 14 pure.) Coated ginger has usually a less bright, delicate hue than ginger from which the cuticle part has been removed, much of it being dark, horny, and resinous.