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POTATO (Solanum tuberosum)
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See also:POTATO (Solanum tuberosum) , a well-known plant which owes its value to the See also:peculiar See also:habit of developing underground slender leafless shoots or branches which differ in See also:character and See also:office from the true roots, and gradually swelling at the See also:free end produce the tubers (potatoes) which are the See also:common See also:vegetable See also:food. The nature of these tubers is further rendered evident by the presence of " eyes " or See also:leaf-buds, which in due See also:time lengthen into shoots and See also:form the haulm or stems of the plant. Such buds are not, under See also:ordinary circumstances, formed on roots. The determining cause of the formation of the tubers is not certainly known, but See also:Professor See also:Bernard has suggested that it is the presence of a fungus, Fusarium solani, which, growing in the underground shoots, irritates them and causes the swelling; the result is that an efficient method of See also:propagation is secured independently of the See also:seed. See also:Starch and other matters are stored up in the tubers, as in a seed, and are rendered avail-able for the See also:nutrition of the See also:young shoots. When grown under natural circumstances the tubers are relatively small and See also:close to the See also:surface of the See also:soil, or even See also:lie upon it. In the latter See also:case they become See also:green and have an acrid See also:taste, which renders them unpalatable to human beings, and as poisonous qualities are produced similar to those of many See also:Solanaceae they are unwholesome. Hence the recommendation to keep the tubers in cellars or pits, not exposed to the See also:light. Among the nine See also:hundred See also:species of Solanum less than a dozen have this See also:property of forming tubers, but similar growths are formed at the ends of the shoots of the common bramble, of Convolvulus sepium, of Helianthus tuberosus, the so-called See also:Jerusalem See also:artichoke, of Sagittaria, and other See also:plants. Tubers are also sometimes formed on aerial branches, as in some Aroids, Begonias, &c. The See also:production of small green tubers on the haulm, in the axils -bf the leaves of the potato, is not very unfrequent, and affords an interesting See also:proof of the true morphological nature of the unclgr ground shoots and tubers. This phenomenon follows injury to the phloem in the See also:lower parts of the See also:stem, preventing the downward flow of elaborated See also:sap. The injury may be due to gnawing See also:insects, and particularly to the fungus Corticium vagum, See also:var. Solani (Rhizoctonia).
The so-called See also:fir-See also:cone potatoes, which are elongated and provided with scales at more or less See also:regular intervals, show also very clearly that the tuber is only a thickened See also:branch with " eyes " set in regular See also:order, as in an ordinary shoot. The potato tuber consists mainly of a See also:mass of cells filled with starch and encircled by a thin corky rind. A few vessels and woody See also:fibres See also:traverse the tubers.
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The See also:chief value of the potato as an See also:article of See also:diet consists in ~ edition of the Herbal was published in 1636 by See also: 517) he 18.8 See also:Water . . . 75.0 gives an indifferent figure of the potato under the name of Papas 3'2 seu Battatas Virginianorum, and adds details as to the method 0.2 loons Nitrogenous Starch, &c. See also:Sugar See also:Fat -a result which approximates closely to the average of nineteen analyses cited in How Crops Grow from Grouven. In some analyses, however, the starch is put as See also:low as 13.30, and the nitrogenous matter as 0.92 (Deherain, Cours de chimie agricole, p. 1J9). See also:Boussingault gives 25'2% of starch and 3% of nitrogenous matter. Warington states that the proportion of nitrogenous to non-nitrogenous matter in the digestible See also:part of potatoes is as r to io•6. The composition of the tubers evidently varies according to See also:season, soils, manuring, the variety grown, &c., but the figures cited will give a sufficiently accurate See also:idea of it. The " ash " contains on the average of See also:thirty-one analyses as much as 59'8% of potash, and 19.1% of phosphoric See also:acid, the other ingredients being in very See also:minute proportion. Where, as in some parts of See also:northern See also:Germany, the potato is grown for the purpose of manufacturing spirit See also:great See also:attention is necessarily paid to the quantitative See also:analysis of the starchy and saccharine matters, which are found to vary much in particular varieties, irrespective of the conditions under which they are grown. It is to the Spaniards that we owe this valuable esculent. The Spaniards met with it in the neighbourhood of See also:Quito, where it was cultivated by the natives. In the Cronica de See also:Peru of Pedro Ciega (See also:Seville, 1553), as well as in other See also:Spanish books of about the same date, the potato is mentioned under the name '` battata " or " papa." Hieronymus See also:Cardan, a See also: In this See also:work (p. 781) it is called " Battata virginiana sive Virginianorum, et Pappus, Potatoes of See also:Virginia." The " common potatoes " of which Gerard speaks are the tubers of I pomoea Batatas, the sweet potato, which nowadays would not in Great See also:Britain be spoken of as common. A secondof cooking the tubers which seem to indicate that they were still luxuries. Chabraeus, who wrote in 1666, tells us that the Peruvians made See also:bread from the tubers, which they called " chunno." He further tells us that by the natives Virginieae insulae the plant was called " openauk," and that it is now known in See also:European gardens, but he makes no mention of its use as an esculent vegetable, and, indeed, includes it among " plantae malignae et venenatae." See also:Heriot (De See also:Bry's Collection of Voyages), in his See also:report on Virginia, describes a plant under the same name " with roots as large as a See also:walnut and others much larger; they grow in See also:damp soil, many See also:hanging together as if fixed on See also:ropes; they are See also:good food either boiled or roasted." The plant (which is not a native of Virginia) was probably introduced there in consequence of the intercourse of the See also:early settlers with the Spaniards. The cultivation of the potato in England made but little progress, even though it was strongly urged by the Royal Society in 1663; and not much more than a See also:century has elapsed since its cultivation on a large See also:scale became See also:general. Botanists are agreed that the only species in general cultivation in Great Britain is the one which See also:Bauhin, in his Phytopinax, p. 89 (1596), called Solanum tuberosum esculentum, a name adopted by See also:Linnaeus (omitting the last epithet), and employed by all botanical writers. This species is probably native in Chile, but it is very doubtful if it is truly See also:wild farther north. See also:Baker (Journ. Linn. See also:Soc., 1884, xx. 489), has reviewed the tuber-bearing species of Solanum from a systematic point of view as well as from that of See also:geographical See also:distribution. Out of twenty so-called species he considers six to be really distinct, while the others are merely synonyrnous or trifling See also:variations. The six admitted tuber-bearing species are S. tuberosum, S. Maglia, S. Commersoni, S. cardiophyllum, S. Jamesii and S. oxycarpum. S. tuberosum is, according to Mr Baker, a native not only of the See also:Andes of Chile but also of those of Peru, See also:Bolivia, See also:Ecuador and Colombia, also of the mountains of See also:Costa Rica, Mexico and the See also:south-western See also:United States. It seems most probable, however, that some at least of the plants mentioned in the northern part of America are the descendants of cultivated forms. S. Maglia is a native of the Chilean See also:coast as far south as the Chonos See also:Archipelago, and was cultivated in the See also:garden of the Horticultural Society at See also:Chiswick in 1822, being See also:con- sidered by See also:Sabine, in his See also:paper on the native country of the wild potato, to be the true S. tuberosum and the origin of the cultivated forms. This species was also found by See also:Darwin in Chile, and was considered by him, as by Sabine before him, to be the wild potato. Baker refers to the plants figured by Sabine (Trans. See also:Hort. Soc. Lond. v. 24.9) (fig. 1) as being without doubt S. Maglia, but A. de See also:Candolle (Origine See also:des See also:Plan.tes cultivees, p. 40) is equally emphatic in the See also:opinion that it is S. tuberosum. S. Commersoni occurs in See also:Uruguay, Buenos Aires and the See also:Argentine See also:Republic, in rocky situations at a low level. Under (From Sabine's figure in the Trans. See also:Hart. the name of S. Ohrondii it has Soc. Lond., 1324, vol. v. pl. ii. See been introduced into western See also:text.) See also:France, where it is not only FIG. i.—Wild Potato-plant in See also:hardy but produces abundance See also:bloom. (- nat. See also:size.) of tubers, which are palatable, but have a slightly acid taste. S. cardiophyllum, described by See also:Lindley in the Journ. Hort. Soc. is a native of the mountains of central Mexico at elevations of 8000 to 9000 ft. S. Jamesii is a well-defined species occurring in the mountains of See also:Colorado, New Mexico and See also:Arizona, and also in Mexico. In a wild See also:state the tubers are not larger than See also:marbles. S. oxycarpum is a but very distinct tuberous species from POTATO central I The full-sized tubers are, however, preferable to smaller ones, as their larger buds tend to produce stronger shoots, and where cut sets are used the best returns are obtained from sets taken from the points of the tubers—not from their See also:base. Thomas See also:Dickson of See also:Edinburgh See also:long ago observed that the most healthy and productive See also:crop was to be obtained by planting unripe tubers, and proposed this as a preventive of the disease called the " curl," which sometimes attacks the young stems, causing them and also the leaves to become crumpled, and few or no tubers to be produced; in this connexion it is interesting to See also:note that Scottish and Irish seed potatoes give a larger yield than English, probably on See also:account of their being less matured. It has also been noted that the sprouting of the eyes of the potato may be accelerated if, while still unripe, it is taken up and exposed for some See also:weeks to the See also:influence of a scorching See also:sun. The best sets are those obtained from plants grown in elevated and open situations, and it is also beneficial to use sets grown on a different soil.
The earliest crops should, if possible, be planted in a light soil and in a warm situation, towards the end of See also:February, or as early as possible in See also: The crop is not dug up until it has come to maturity. Potatoes are also grown largely in hooped beds on a warm border in the open ground. The sets after having been sprouted, as above, are planted out in January in trenches 2 ft. deep filled with hot dung, the sets being planted 5 in. deep, and over all radishes are sown. The ridges are then hooped over, allowing about 2 ft. of space in the middle, between the mould and the hoop, and are covered with mats and straw, but as soon as the radishes come up they are uncovered daily, and covered again every See also:night as a See also:protection against possible frosts. This is continued till the potatoes are ready for digging in May. Potatoes are sometimes grown in pots in See also:heat, sprouted sets being planted in 11-in. pots about two-thirds full of soil, and placed near the See also:glass in any of the forcing-houses, where a temperature of from 65° to 7o° is to be maintained. The plants are duly watered and earthed up as they advance in growth. little known Mexico.' A See also:review of the localities in which the presence of S. tuberosum and its tuber-bearing See also:allies has been ascertained shows that, broadly, these varieties may be divided into mountainous and littoral. In either case they would not be subjected, at least in their growing season, to the same extremes of heat, See also:cold and drought as plants growing on inland plains. Again, those forms growing at a high See also:elevation would probably start into growth later in the season than those near the coast. The significance of these facts from a cultural point of view is twofold: for, while a late variety is desirable for culture in Great Britain, as ensuring more or less See also:immunity from See also:spring See also:frost, it is, on the other See also:hand, undesirable, because late varieties are more liable to be attacked by the potato disease (Phytophthora infestans) which as a See also:rule appears about the time when the earliest varieties are ready for lifting, but before the late varieties are matured. In cultivation the potato varies very greatly not only as to the season of its growth but also as to productiveness, the vigour and luxuriance of its foliage, the presence or relative See also:absence of hairs, the form of the leaves, the size and See also:colour of the See also:flowers, &c. The tubers vary greatly in size, form and colour; gardeners See also:divide them into rounded forms and long forms or " kidneys," and there are of course varieties inter-mediate in form. The colour of the rind, yellowish, See also: The " sets " are then planted in rows at a distance varying from 15 in. to 3 ft., the distance being regulated by the height of the stems, and that between the sets varying from 6 to 12 in., 8 in. being a good average space for garden crops, with 2 ft. between the rows. The sets may be put in 6 in. deep. The planting of whole tubers instead of the cut sets usually gives a better return. ' Although these six are the only species admitted as such by Baker, it is well to note some of the varieties. The S. etuberosum of Lindley, differing from the common S. tuberosum in not producing tubers, was found in Chile, and is probably not specifically distinct, although exceptional, for it is by no means very unusual to find even cultivated plants produce no tubers. S. Fernandezianum is, according to Baker, a form of S. tuberosum, but if so its See also:habitat in the See also:mountain See also:woods of Juan See also:Fernandez is climatically different from that in the dry mountains of central Chile, where the true S. tuberosum grows. S. otites was found more recently by See also:Andre on the See also:summit of Quindiu in Colombia, at a height of 11,483 ft. It produces tubers of the size of a See also:nut. S. Andreanum, found by Andre at See also:Cauca (6234 ft.), was considered by the traveller to be the true S. tuberosum, but this view is not shared by Baker, who named it after the discoverer. Its tubers, if it produces any, have not been seen. S. immite is probably only a slight variety of S. tuberosum, as are also the Venezuelan S. colombianum, S. verrucosum, S. demissum and S. utile. S. Fendleri, a native of the mountains of New Mexico and Arizona, was considered by See also:Asa See also: Additional information and CommentsThere are no comments yet for this article.
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