Potato (Span, batatas, the name for sweet potato, erroneously transferred to a very different plant), the plant and tuber of solanum tuberosum. The genus solanum contains over 900 described species; it includes annual and perennial herbs, shrubs, and even trees, which, though widely distributed, are more abundant in tropical South America than elsewhere; it is the typical genus of a large and important family, the solanacea, in which there are about 60 genera. Tobacco, stramonium, belladonna, and henbane are powerful narcotics belonging to the family; and besides the potato, it furnishes as esculents the tomato, egg plant, capsicum, and physalis or winter cherry. The leading characters of the genus solanum are a five-parted calyx; a five-lobed, wheel-shaped corolla, with scarcely any tube; stamens five with very short filaments, their anthers converging to form a cone around the pistil, each anther cell opening by a pore at the top; ovary two-celled, with a simple style, and in fruit becoming a two-celled, many-seeded berry.
There are several species belonging to the tuber-bearing section, two of which, S. Fend-leri and 8. Jamesii, are found in the mountains of New Mexico. - The potato is one of the few generally cultivated plants that are well known in the wild state, and concerning the origin of which there is little room for discussion. There is abundant evidence that it grows wild at the present day in Peru and Chili, on the island of Chiloe, and elsewhere; it is probable that there are four or five varieties in the wild state, and not unlikely that some of those described as distinct tuber-bearing species are forms of 8. tuberosum. The potato was carried to England in Sir "Walter Raleigh's vessels from Virginia in 1586; but there is good reason to believe that it had been introduced into Spain much earlier from Quito; in 1588 it was sent to Flanders from Italy, where it had been received from Spain, and was at that time a common article of food, and was even fed to the pigs. Moreover, it is thought that its occurrence in Virginia was due to a recent introduction by the Spaniards; there is no proof that it was in cultivation by the aborigines of this country or those of Mexico. After its introduction into Europe the potato made very slow progress, and it is only within 100 years that its cultivation has been common even in Ireland, a country which since then has so largely depended upon it.
In the most important gardening work of its time, published in 1771, only two varieties of the potato are mentioned, a white and a red. Though popularly called a root, the tuber of the potato is really an underground stem (see Plant), enlarged by the accumulation of starch, which is there stored up for future use. The true nature of the tuber may be best seen by carefully taking up a young plant just as the potatoes are beginning to form; besides the proper roots there will be found stems, longer or shorter according to the variety, the ends of which and their branches have begun to swell to form tubers; usually a plant will show every gradation, from the merest swelling to well formed if not large tubers. The leaves upon these underground branches are represented by scales, often conspicuous when the tuber is young, and when it is full grown appearing as a distinct scar. In the axils of these rudimentary leaves are found the buds for next year's growth, popularly called the eyes of the potato, and these may consist of a central bud with several accessory buds on each side of it, or, in some varieties with prominent eyes, as a sort of suppressed branch with buds crowded upon it.
That this is the real nature of the tuber is shown by the fact that under favorable circumstances the branches above ground will take on a similar development. As it has been cultivated for generations with a view solely to the improvement of the tubers in size and number, the other parts of the plant have diminished; in the natural statethe portion of the plant above ground is large and vigorous, while the tubers are small and few; in cultivation the tuber has been developed to such an extent that the stems are comparatively weak, and many varieties do not flower and produce seeds. The vine, as it is popularly called in this country (in England the haulm), in the different cultivated kinds, presents considerable variety in size and vigor, while the leaves differ in the amount of subdivision and also in their color. The flowers in some varieties are twice as large as in others, and vary from white and bluish white to a handsome light purple; the berry, or seed ball, usually about an inch in diameter, is yellow or purplish.
In common with many other solanums, the herbage and fruit of the potato contain the alkaloid solanine, an exceedingly active poisonous principle, four grains of which will kill a dog; an extract prepared by evaporating the juice of the herb has been used in medicine as a narcotic in doses of one eighth to one half grain. The foliage of the potato may be regarded as poisonous, but the dangerous principle does not exist in properly grown and carefully kept tubers; these are mainly starch, and this, wherever it occurs, or however acrid and poisonous may be the plant producing it, is always wholesome. But sola-nine is developed in the sprouts which form upon the tubers, and in the skin of the tuber when exposed to the light; some varieties have a tendency to form potatoes so near the surface that they become exposed by the washing away of the soil; such tubers are green where exposed, and are very acrid and unfit for food; the same thing happens when potatoes after digging are long exposed to light; any sense of acridity in the throat after eating potatoes indicates that they have been improperly kept, and should be rejected. - The potato may be multiplied in three ways: by division of the tuber, the ordinary method in cultivation; by cuttings of the stems, which take root readily in a proper propagating frame, a method sometimes resorted to for the rapid multiplication of a rare variety; and by seed.
The first two processes only subdivide the individual, while from the seed new varieties are obtained; several of the newer and most valuable varieties now in cultivation, but which differ greatly in size, form, color, and time of maturing, were from the seeds contained in a single seed ball, which had been saved by the merest accident. The seeds are sown in a hotbed in February or March, and when danger of frost is over the plants are transferred to the open ground. At the end of the season the tubers are of good size and have their qualities sufficiently manifested to show whether it is worth while to give them further trial. Within the past ten years more new varieties have been produced than in all previous years. In ordinary cultivation small potatoes are planted whole; those of moderate size are cut into two or three pieces, or good-sized tubers are cut into single eyes. The first named method is habitually followed only by careless farmers; in case of scarcity of seed (as the tubers for planting are called) small refuse potatoes may be used without any perceptible change the first season, but the continuous planting of small tubers year after year tends to diminish the size of the whole crop.
If a whole large tuber be planted, a few of the shoots which start first will appropriate all the nutriment, and a large proportion of the eyes will remain dormant. The object is to give each bud or eye sufficient nutriment to sustain the growth of the shoot until it forms roots. Good-sized, well formed potatoes cut to single eyes are the best; in cutting care is taken to give each eye as much of the tuber as possible. Where it is desired to make the most of a rare kind, the eyes are sometimes divided into two or three pieces; as each eye usually has several buds, this division is practicable. The end of the potato nearest to the plant is called the stem end, and the opposite the seed end; at the seed end the eyes are much more numerous than elsewhere, and, being more excitable than the others, start first. In the experiments of Dr. F. M. Hexamer of New Castle, N. Y., out of 100 potatoes planted whole, 98 started from the seed end. His experiments show that the potato, like other branches, has the power of producing adventitious buds; he peeled 70 potatoes so that no eyes were visible, and planted them in separate hills; half the number produced shoots and ripened a crop, and out of 80 hills planted with pieces without eyes, but having their portion of skin, 13 grew, and in every case the sprout started from the cut surface.
When a potato is placed in sufficient heat to excite growth, but under circumstances unfavorable to the development of leafy branches, a singular transference of nutriment takes place; tho starch and other principles of the old tuber, which in favorable conditions would have been expended in producing shoots, here produce new tubers; and it is not unusual to find late in spring, at the bottom of a barrel or bin where light has been completely excluded, specimens with small new potatoes attached to them. In this way gardeners sometimes produce new potatoes in winter; tubers of the preceding year's growth are kept as cool as possible, and in a dry place, with a view to retard vegetation; such sprouts as push are broken off, and in autumn the tubers thus prepared are placed in layers with light soil, in boxes, in a dark place where the temperature is from 50° to 60°; in about three months a crop of small potatoes is produced at the expense of the large ones. Occasionally a new potato, or several, are found in the interior of an old one; this is probably due to a growth similar to the one just mentioned, which takes place when the potato is so pressed upon by others that its comparatively soft interior offers less resistance to the development of the sprout or new tuber in this direction than there would be in any other. - The potato succeeds best in a temperate climate; in tropical countries it is superseded by the sweet potato, yams, and other plants, though wherever English-speaking people colonize they endeavor to cultivate the potato.
The number of varieties is now very large; Dr. Hexamer, before referred to, keeps. up a collection of over 300 named sorts as a standard with which to compare new varieties. The varieties so much esteemed in England do not as a general rule succeed in the United States, while American sorts were considered as not worth cultivation in England until they were tried at the gardens of the royal horticultural society and awarded first class certificates without their names or origin being known. But few of the kinds in general cultivation before the advent of the rot, in 1845, are now to be found. (See Potato Rot.) The Rev. 0. E. Goodrich of Utica, N. Y., regarding the failure of the potato as due to a weakness resulting from long cultivation by division, which not only rendered it less productive . but more susceptible to diseases, commenced about 1850 a series of experiments with a view to the introduction of more vigorous varieties. He procured a fresh stock from the native localities in South America, from which he raised thousands of seedlings; his experiments in crossing and raising seedlings were continued for several years with great care, and when he produced a variety of unusual promise he sent it to various persons for trial; before he had seen the full results of his labors he died, without other reward than a few hundred dollars sent him as a testimonial.
While but few of his varieties maintain a place in cultivation, most if not all the excellent kinds now grown are due to his labors. The great step in modern potato culture was the production of the early Rose, which is a seedling from one of Mr, Goodrich's very hardy and productive varieties, the garnet Chili, which has also produced other sorts of great value. The Mercer (also called Chenango and Meshannock), Carter, pink-eye, and other highly esteemed varieties of 30 or 40 years ago, are now scarcely to be found; among the leading market varieties are garnet Chili, Jackson white, peachblow, early Goodrich, and early and late Rose; while these bid fair to be superseded by a new set, in which quality and productiveness appear to have reached their utmost limits; these kinds include Alpha, Snowflake, early Vermont, Brownell's Beauty, and others of the highest excellence, and manifesting an improvement which the unselfish labors of Mr. Goodrich only rendered possible. Potatoes vary in earliness, form, size, color, the number of eyes and their elevation or depression from the surface, the smoothness or roughness of the skin, and keeping qualities; in the New York market round white-skinned varieties will sell more readily than those of different shape and color, though they may be of better quality.
Bermudas are the first new potatoes that appear in our markets; they are raised from seed sent from this country; the western red and garnet Chili, both coarse kinds, grow in Bermuda in the winter, and come here in early spring; as the summer of the island is too hot for keeping them, seed potatoes are sent out annually. Following these our markets are supplied from Georgia and the Carolinas, then from Virginia, and so northward, keeping up a constant succession of new potatoes. Early potatoes may be essentially forwarded by placing the seed tubers in a warm place until they sprout, then cutting them into sets, taking care not to break the sprouts, and planting them in a frame without glass, but covered with mats or shutters at night and in cold days. As a farm crop more regard is had to productiveness and keeping qualities than to earliness; a good rich loam that has been highly manured for some previous crop, or a recently turned sod, is most suitable; the use of fresh manure, though common, is regarded as inducing rot and a bad quality of tuber; ashes, salt, and gypsum are useful fertilizers, and ground bone is much used.
Potatoes are valuable for preparing new land, or that which has become weedy, for other crops; for this purpose they are planted in hills three feet or more apart each way. On land in good condition they are often planted in drills about three feet apart, the sets being dropped a foot apart in the drill. The old plan of heaping the earth around the plant, or hilling, is abandoned except in cold damp soils. The crop is kept as clean as possible, but after the tubers begin to form the culture should be very shallow. The yield of tubers is said to be increased by picking off the flower buds, though it is seldom practised. When the tubers are ripe the tops die. Numerous machines have been devised for digging potatoes, but none of them are in general use. For reasons already given potatoes should not be exposed to the sun when dug, but may be dried in small heaps covered with tops; they are stored in pits or heaps covered with sufficient straw and earth to prevent freezing, or in cellars, which should be kept at as low a temperature as possible without freezing. - The value of potatoes as food depends upon the amount of starch they contain, and this is indirect relation to their specific gravity; according to Pohl, those of sp. gr. 1.090 contain 16.38 parts of starch in 100, while those of sp. gr. 1.123 yield 24.14. The amount of starch varies with the season, unripe tubers containing scarcely two thirds as much as those thoroughly mature; and again in spring, when vegetation begins, the starch perceptibly diminishes.
An average of 19 analyses by Grouven of various kinds of potatoes, freshly dug, gave water 76.00, albuminoids 2.80, starch 15.24, besides cellulose, gum, and other principles, and 0.95 of ash. The amount of ash varies from 0.88 to 1.30 in 100 parts, and this is more than half potash. As an article of food potatoes are deficient in albuminoids and phosphates, and among the Irish peasantry, where they form a large portion of the diet, the custom of eating them with buttermilk or skim milk is founded upon correct principles, as these supply the elements in which the potato is deficient. According to Smith ("Foods" in the "International Scientific Series "), " more than 2 1/2 lbs. of potato are required to equal 1 lb. of bread in carbon, and more than 3 1/2 lbs. in nitrogen." Tastes in regard to the quality of potatoes and methods of cooking them vary greatly; the general preference is for a dry floury ball of starch, with an absence of all flavor. The Irish boil them only so much as to leave the centre still a little hard, or " with a bone in it." Although in some parts of France potatoes are almost as largely consumed as in Ireland, the French generally do not regard them as essential to a meal, and rarely eat them plain boiled, but dressed in some of the many forms peculiar to the country; the German finds them most acceptable as a salad.
Potatoes are used to some extent as a food for domestic animals, especially for swine; fed occasionally to horses, they are an excellent corrective of the digestion. Their antiscorbutic property renders them valuable on sea voyages, and they form a part of the dietary in prisons on this account. During the mining excitement in California, where men lived almost exclusively upon salt meat and fine flour, land scurvy was very prevalent, but yielded to potatoes, which met with a ready sale at $1 each, to be eaten raw. A thin slice of the potato examined with the microscope shows very large and thin cells filled with starch grains, which are about 12 in number in each cell, much larger than any others of the ordinary forms of starch, and distinctly marked with concentric lines. Potatoes are largely used in the manufacture of starch (see Starch), and in Europe are distilled to produce spirit. - According to the census of 1870, the total production of potatoes in the United States was 143,337,473 bushels, of which New York produced 28,547,593 bushels, Pennsylvania 12,-889,367, Ohio, 11,192,814, Illinois 10,944,790, Michigan 10,318,799, Maine 7,771,009, Wisconsin 6,646,129, Iowa 5,914,320, Indiana 5,399,-044, Vermont 5,157,428, New Jersey 4,705,-439, New Hampshire4,515,419, Missouri 4,238,-361, and Massachusetts 3,025,446.
Fig. 1. - Tubers in different stages of development.
Fig. 2. - Branch developed as a Tuber.