PORTULACA 



POTATO 



1417 



tries; probably native to the southwestern parts of the 

 U. S., but it is considered that it is introduced into the 

 East and North. In sandy and loamy soils it is one of 

 the commonest and most persistent of weeds, but it is 

 little known on heavy lands. The common wild plant is 

 prized for "greens" in some regions, but the French up- 

 right forms (Fig. 1928) are much better, as they are 

 larger and more tender; these improved varieties look 

 very different from the common " Pusley " ; they are easy 

 of culture. For a discussion respecting the nativity of 

 Purslane in North America, see Gray & Trumbull, Amer. 

 Jour. Sci. 25, p. 253. L. H. B. 



1928. Portulaca oleracea, the cultivated upright form (X %). 



POSOQUfiKIA (from a native name in Guiana). 

 Rubiacece. About a dozen tropical American glabrous 

 trees and shrubs with thick opposite entire Ivs., tubular 

 fragrant white, rose or scarlet fls. in terminal corymbs, 

 and a berry-like fruit. The fls. are 5-merous: ovary 

 1-2-loculed, the style with 2-parted stigma. Several 

 species are mentioned in Old World horticultural litera- 

 ture, all warmhouse plants, but only one has appeared 

 in the American trade, P. longifldra, Aubl. (sometimes 

 erroneously written P. longifolia). This species is na- 

 tive to French Guiana. It is a handsome free-flowering 

 bush 5-8 ft. high : Ivs. oblong-acuminate, narrowed at 

 the base, thick and shining: fls. 12 or more in a cluster, 

 3-5 in. long, waxy white, very fragrant, the slender tube 

 curved, hairy in the throat. Prop, by cuttings of ripen- 

 ing wood. L. H. B. 



POT, See Potting and Pots. 



POTAMOGETON (compound of Greek words signify- 

 ing that these are river plants) . Naiadacew. POND- 

 WEED. A rather large genus (50 or CO species) of 

 aquatic plants in temperate and sometimes in tropical 

 regions, a few of which are sometimes grown in aquaria 

 and ponds. Nearly 40 species are native to North 

 America. They are weedy plants, attaching themselves 

 to the bottom in ponds, lake margins and in shallow 

 streams, and holding their small spikes of inconspicuous 

 flowers above the water in midsummer. In many of the 

 species there are two kinds of leaves, the narrow sub- 

 merged ones and the broad floating ones. The small 

 perfect flowers have 4 greenish perianth-segments, 4 sta- 

 mens, and usually 4 sessile 1-ovuled ovaries: fr. a nut- 

 let with a coiled or hooked embryo. The Potamogetons 

 are very difficult plants for the systematic botanists, 

 and it is not worth while to describe any of the species 

 here. There are none which are generally known in the 

 trade. They are likely to be weeds in lilf ponds. For 

 the Amer. species, see Morong, Mem. Torr. Club. 3, No. 



2; also the current manuals. Three species have come 

 into slight notice in American gardens: P. crispus, 

 Linn., and P. natans, Linn., natives, and P. densus, 

 Linn., European. Easily grown. L jj. g < 



POTASH. See Fertilizers and Fertility. 



POTATO is one of the most widely cultivated and 

 valuable of esculent tubers. It is Solatium tiiberosum 

 of the botanists, and is allied to several powerful nar- 

 cotics, such as tobacco, henbane and belladonna, and 

 also to the tomato, eggplant and capsicum. The Potato 

 is a native of the elevated valleys of Chile, Peru and 

 Mexico, and a form of it is found in southern Colorado 

 (see Solatium). It probably was carried to Spain from 

 Peru early in the sixteenth century. It seems to have 

 been introduced into Europe as early as 1505. Sir Wal- 

 ter Raleigh, in 1585, is said to have brought back the 

 Potato from the "new country." Recent investigation, 

 however, seems to give the credit of introducing the 

 Potato into England to Sir Francis Drake, in 1586. As 

 Batatas Virginiana it was figured and described by 

 Gerarde in 1597. It is probable that these circum- 

 stances led to erroneously giving the credit of intro- 

 ducing the Potato to Raleigh instead of to Sir John 

 Hawkins. The wild varieties in their native habitat 

 still bear a close resemblance to cultivated varieties 

 except for the enlarged vine and abnormal development 

 of the tubers in the latter. During the seventeenth cen- 

 tury the Potato was cultivated in gardens in several 

 European countries. It was recommended by the Royal 

 Society of London in 1663 for introduction into Ireland 

 as a safeguard against famine. The cultivation of the 

 Potato as a field crop became somewhat common in Ger- 

 many soon after 1772, at which time the grain crops 

 failed and Potatoes were a welcome substitute for the 

 bread-corn. It was near the middle of the eighteenth 

 century before it acquired any real importance in Eu- 

 rope, outside of Ireland and a few restricted localities 

 in other countries. As late as 1771 only a white and red 

 variety were mentioned in one of the most important 

 English works on gardening. The plants were enor- 

 mously productive, but the tubers were poor in quality, 

 so poor in fact that their chief use was as food for 

 domestic animals; and only when the bread-corns 

 failed were they used to any extent, and even then as a 

 substitute. By 1840 the Potato had been largely substi- 

 tuted in Ireland for the cereals and other similar food 

 crops, as the yield of Potatoes in weight exceeded by 

 twenty to thirty times the yield of wheat, barley or cats 

 on an equal amount of land. This large dependence on 

 a single food crop finally resulted in a wide-spread 

 famine. The Potato blight which appeared in the United 

 States in 1845 devastated Ireland in 1846. During two 

 years, 1846 and 1847, a conservative estimate places the 

 numbers who perished for want of food or from dis- 

 eases caused by a meager diet of unhealthy and unnu- 

 tritious food at 600,000. By 1848 the plague had virtually 

 disappeared. 



The roots of the Potato are distinct from the tubers. 

 Usually, two to four roots start from the stalk at the 

 base of each underground stem which, when enlarged 

 at the end, forms the Potato. See Fig. 1929. Roots may 

 also start where underground stems are wanting. The 

 Potato is a perennial plant. The accumulated starch in 

 the tubers furnishes an abundant supply of nourish- 

 ment for the plants growing from the eyes or buds un- 

 til they are well above ground. So much food is stored 

 that not infrequently small young tubers are formed on 

 the outside of Potatoes left in the cellar during the 

 summer. Potatoes grow from two to even three feet 

 high, have smooth, herbaceous stems, irregularly pin- 

 nate leaves, and wheel-shaped flowers (Fig. 1930) vary- 

 ing in breadth from 1 to 1% inches and in color from 

 bluish white to purple. They bear a globular purplish 

 or yellowish fruit or seed-ball of the size of a goose- 

 berry, containing many small seeds. 



The dry matter of Potatoes is composed largely of 

 starch. Being deficient in nitrogen, the Potato is ill- 

 adapted for an exclusive diet, and should be used in 

 connection with food containing a high percentage of 

 proteids, such as lean meats, peas, beans and egrgrs. 

 The lack of vegetable fats may be supplied by butter, 



