This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
Continued from page 509.
The flowers are dioecious, that is, the sexes growing on different plants, disposed in speci-form branches at the junction of the leaves. The corolla of the males is composed of six petals of a pale-yellow color ; the three outermost ones rounded, and the three inner smaller ones of a roundish oval. The stamens, six in number are extremely small, though well defined ; and the anthers are oval and supported by short filaments, grouped freely in the centre of the flower. As the male plant only has been introduced, the female cannot be described, and consequently no seeds produced before the latter can be produced.
The roots, or tubers, vary in length and thickness, according to the nature of the soil, in reference to lightness, depth, and tenacity, which, no doubt, influences their form and mode of development. The maximum size to which they grow is about two inches in diameter, the larger end taper-ing upwards to the size of the finger, as indicated in the cut aside. They are covered by a brownish fawn-colored skin, pierced by numerous rootlets. Under this envelop, is a cel-lular tissue of a white opal color, very crispy, filled with starch and a milky, mucilaginous fluid, with scarcely any ligneous fibre. In cooking, this tissue softens and dries, but to a greater degree, like that of the common potato, the taste of which it much resembles. Each plant often produces several tubers, though generally it has but one. They usually weigh about half a pound each, but sometimes three pounds, running perpendicularly into the earth to the depth of a yard. M. Decaisne, of France, says, however, that those cultivated by him rarely exceeded 15 to 20 inches in length.
The cultivation of this yam appears to be easy and simple. M. Decaisne, in the " Revue Horticole," for 1854, has described the method adopted in China, which is nearly as follows: In autumn they choose the smallest tubers, which they preserve from injury by frost by covering them in a pit with earth and straw. The spring succeeding, they plant them near each other in a trench, in well-prepared soil. When they have put out shoots one or two yards in length, they cut off the joints and leaves containing the buds and plant them for production. For this purpose, they form the ground into ridges, on the top of which a shallow trench is made with the hand or some suitable implement, in which these joints are planted, covering them slightly with fine earth, with the leaves rising just on the surface. Should it rain the same day, they shoot immediately ; if not, they water them gently until they do. In fifteen or twenty days, they give birth to new tubers and stalks, the latter of which it is necessary to remove from time to time, to prevent them from taking root on the sides, and thus injure the development of the tubers already formed.
The method which has been found to answer best in France, according to "Le Bon Jardinier," for 1855, consists in catting the tubnrs into fragments of moderate size, placing their crowns, or eyes, in small pots, in April, and then transplanting them into a deep, rich soil as soon as the spring frosts are no longer to be feared. Notwithstanding the plant has a tendency to plunge its roots into the earth perpendicularly, any distortion to which it might be liable in the pot will not be in the least prejudicial to its future growth, as is the case with other yams. It is even thought that its cultivation in largo pots, buried under ground, might be successfully adopted in some cases, particularly where the soil is of a permeable nature, which would allow it to extend its roots to a depth of more than a yard.
If it is desired to multiply the plant rapidly, in a high latitude, it can be done by means of suckers, or slips. To this end, there may be cut in June or July as many slips as there are sets of leaves on the vine, and plant them side by side under a glass in a light, sandy soil, sufficiently deep for the bud at the base of the leaves merely to be covered. The better way is to let the leaves remain entire, unless they are disproportion ably large. In about five or six weeks, the slips will take root, and present at the angle of each leaf a small tuber about the size of a pea, as denoted in the cut.
These scarcely increase in size during the season, but become sufficiently ripened, on ceasing to water them, to replant in the spring, when they will grow with as much vigor as if produced from the cut tubers, as shown in the figures below.
In this manner, each plant may be made to yield a hundred fold. The reproduction from the vines, however, may be brought about in more temperate latitudes, by planting them in a garden in the open air. In this case, it is better not to cut up the vines, but to bury them horizontally just below the surface, with the midrib of the leaves resting on the ground. Should there not be sufficient rain, the soil must be kept moist by slight waterings at the close of the day.
If we may judge by the stagnation of its vegetation during drought, this plant seems to require irrigation, or watering. The leaves and vines are small considering the size of the roots, and will probably allow of close planting, say eight or ten to the square yard. The vines in general, when not propped up, spread over the ground without taking root, intertwining with each other ; but do not grow to that length as when propped up by poles or stakes. In one instance, in France, a strong pole about ten feet in height above ground was inserted near one of these plants, which wound itself regularly around it and soon overreached its top. This yam requires no cultivation other than that of eradicating the weeds, as the operation of earthing-up is regarded as quite superfluous.
What may be the result of meteorological influences on this product in different climates and seasons cannot at present be determined. In the neighborhood of Paris, last year it made rapid progress ; the long vines growing vigorously and putting forth an abundance of leaves. Towards August, many flowers of the male kind appeared, and by the middle of September the vegetation was insensibly checked, assuming a yellow tint, indicating that the period of maturity of the tubers was near at hand, which, however, were not dug before the 6th of November.
The expense of labor may be more than that of the potato, but it will be amply compensated by the prolific result To facilitate the extraction of the tubers from the earth, it is recommended that they be planted as near as practicable in bunches, or hills.
This root, it will be seen, is voluminous, rich in nutritive matter, and can be cooked in every respect like the common potato, and can even be eaten in the raw state. It also bids fair to become a source of as much profit to the cultivator, richer in fact in nutriment, and therefore is believed to be destined to render even greater service to the world.