PORTULACA 



tries, piobably nitue to the southwestern parts of the 

 U ^5 but It IS ooiiMtlered that it is introduced into the 

 East and North In sandy and loamy soils it is one o£ 

 the commonest and most persistent of weeds but it is 

 little kn ju n on he i\ > lands The common w ild plant is 

 prized for ^leens in some regions, but the Fiench up- 

 right forms (tig 1^28) vie much bettei as they are 

 larger and more tender, these impro\ed v-meties look 

 very different fiom the ( onimou Push \ thejareeasy 

 of culture For a discussion respecting the nativity of 

 Purslane in Noith America seeCiaj i, riumbull Amer. 

 Jour Sci _', p J)( L H. B. 



1928. Port 







Itivated uprieht lo 



'A). 



POSOQUfiRIA (from a native name in Guiana). 

 liitbiAceif. About a dozen tropical Aniericau glabrous 

 trees and shrubs with thick opposite entire Ivs., tubular 

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

 and a berry-like fruit. The lis. 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. loiiijifolia ). This species is na- 

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

 liusli ry-iy ft. high: Ivs. oblong-acuminate, narrowed at 

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

 :f-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. Sec PnlthKj and Pols. 



POTAMOGfiXON (compound of Greek words signify- 

 ing that thes,. an- rirer plants). JVaiaddci'ip. Pond- 

 weed. .\ rather large genus (50 or CO species) of 

 af{uatic 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 pon.]^, hno Margins and in shallow 

 streams, and holdini; 1 1 i - uf inconspicuous 



flowers above the wain n ! , . i-. In many of the 

 species there are two Lim: .i !■ i .' ^, the narrow suli- 

 merged ones and the i.i..utl il,.aiiiii; ones. The small 

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

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

 let with a coiled or hooked embryo. The Potaniogetons 

 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 generallv known in the 

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

 theAiner. species, see Morong, Mem. Torr. Club. 3, No. 



2; also the current manuals. Three species have come 

 into slight notice in American gardens: P. crlspus, 

 Linn., and P. natans, Linn., natives, and P. dSnsus, 

 Linn., European. Easily grown. l. jj. B. 



POTASH. 



ilizers and Fertility. 



POTATO is one of the most widely cultivated and 

 valuable of esculent tubers. It is Solatmm tuberosum 

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

 cotics, such as tobacco, hcnl.ain' and belladonna, and 

 also to the tomato, eggplaiii an. I . aiiinnii. The Potato 

 is a native of the elevaie.l xall.>s,.i rhile, Peru and 

 Mexico, and a form of it is tiMin.l >u southeru Colorado 

 (see ijoldiniiii). It |Mol.a!.|y «as earried to Spain from 

 Peru early in the siM.eTiiii e.iitui-y. It seems to have 

 been introduced ini.. i:iii.i|„. as ,.arly as 15G5. Sir Wal- 

 ter Raleigh, in las,',, is said i.i have brought back the 

 Potato from the "uew country." Recent investigation, 

 however, seems to give the credit of introducing the 

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

 Butatas riiyitiiana it was figured and described by 

 Gerarde in ioUT. 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 

 Societv of London in WKi 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 whi<'h 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 oats 

 on an equal amount of land. This large dependence on 

 a single food crop tinally 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 bv a meager diet of unhealthv 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 u-iderground 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. 19.10) vary- 

 ing in breadth from 1 to 1 '4 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 eggs. 

 The lack of vegetable fats may be supplied by butter, 



