PORT 



QLty ®reaguri? of 3Sotang. 



922 



and indehiscent. They are found in various 

 parts of the world— chiefly, however, in 

 South America and at the Cape of Good 

 Hope— and always inhabit dry parched 

 places. They have a great affinity to Caryo- 

 phyllacece, from which they are chiefly 

 distinguished by their bisepalous calyx, 

 perigynous stamens, and transversely de- 

 hiscent capsule. Genera eighteen ; species 

 196. Examples : Portnlaca, Talinum, Clay- 

 tonia. [J. H. B.] 



PORTULACA. The typical genus of Por- 

 tulacacece. It contains between thirty and 

 forty species, fully two-thirds of which be- 

 j long to the tropics and subtropics of the 

 I western hemisphere, and the remainder 

 I to tropical Africa, India, Australia, and the 

 Sandwich Islands ; while the Common Purs- 

 lane, P. oleracea, is naturalised in most 

 warm parts of the world. All are low suc- 

 culent herbs, with alternate or irregularly 

 opposite flat or nearly cylindrical leaves, 

 often with tufts of bristles in their axils, 

 and the upper ones forming an involucre 

 around the solitary or clustered flowers; 

 the latter being yellow purple or rose- 

 coloured and very ephemeral, expanding 

 only once, and that only in direct sunshine 

 during the forenoon. 



P. oleracea, the Common Purslane, is a 

 prostrate annual seldom more than six 

 inches high, glabrous, with small oblong 

 I wedge-shaped leaves destitute of bristles 

 in their axils, and small stalkless clus- 

 tered or solitary yellow flowers above the 

 last leaves on the branches. Purslane 

 has been cultivated from very ancient 

 times, and is now spread over the tropics 

 and both temperate zones. It possesses 

 antiscorbutic properties, but is not much 

 employed in this country, though its young 

 shoots are sometimes put in salads, and the 

 older ones used as a potherb or for pick- 

 ling. Three varieties, the Common Green,, 

 the Golden, and the large-leaved Golden, 

 are grown in gardens. [A. S.] 



POSO. A sort of beer made of the fer- 

 mented seeds of Zea Mays. 

 I POSOQIJERIA. A genus of shrubs or 

 small trees, natives of Guiana, the West 

 Indies, &c, and included among the Cin- 

 chonacece. They are remarkable for their 

 very long white hanging flowers, the co- 

 rolla of which is funnel-shaped, with a 

 very long tube, a hairy throat, and a five- 

 parted limb ; stamens five, protruding from 

 the corolla and attached to its throat, 

 the filaments wavy ; style thread-like, con- 

 cealed within the tube of the corolla; 

 stigma with two slender lobes. Fruit suc- 

 culent, crowned by the limb of the calyx, 

 two-celled. Some of the species with long 

 white flowers are cultivated as stove plants 

 in this country. The generic name is a 

 modification of the native name applied 

 to P. longiflora in Guiana. [M. T. M.] 



POSTICOUS. Turned away from the 

 axis of a flower, as some anthers whose 

 dehiscence takes place next the petals; 

 also, stationed on that side of a flower 

 which is next the axis. 



POTALIA. A genus of Loganiacece al- 

 lied to Fagrma, but well characterised by 

 the great number (usually ten) of the lobes 

 of the corolla and of the stamens, whilst 

 that of the lobes of the calyx is four only. 

 There is probably but one South American 

 species, a weak shrub or undershrub, quite 

 glabrous, with long opposite rather thick 

 leaves, and axillary flowers. The juice is 

 bitter and acrid, as in Gentianacece ; and an 

 infusion of the leaves, slightly mucilagi- 

 nous and astringent, is used in North Brazil 

 as a lotion for the eyes. The tropical Afri- 

 can Antlwcleista differs in so few essential 

 points that it might be considered as a 

 second species of Potalia. 



POTAMOGETONE.E. The same as Jun- 



caginaceaz. 



POTAMOGETON. The Pondweed : a ge- 

 nus of submersed or partially floating aqua- 

 tics belonging to the order Juncaginaceoz, 

 of which the characters are :— Flowers per- 

 fect, four-cleft; stamens and styles four; 

 seed-vessels four, sessile. There are nearly 

 twenty species of Pondweed indigenous in 

 our lakes, ponds, and rivers, all having 

 very cellular stems and leaves, and unat- 

 tractive greenish flowers often collected 

 into a spike. One group is represented by 

 P. natans, of which the lower leaves when 

 present are submersed very long and nar- 

 row ; theupper broadly elliptical, of a coria- 

 ceous texture distinctly marked with lon- 

 gitudinal veins, of a glossy green hue, and 

 furnished with long flaccid stalks by means 

 of which they accommodate themselves to 

 j a varying depth of water, and are always in 

 a floating position. P. crispus, P. densus, 

 P. per/oliatus, &c, have only submersed 

 leaves which are alternate and pellucid, 

 resembling when artificially dried a thin 

 animal membrane. P. zosterwfolius and P. 

 gramineus have only submersed leaves, 

 which are very long and narrow and of a 

 texture resembling that of Zoster a. P. pu- 

 sillus and others bear also submersed leaves 

 of an olive-brown hue, and so narrow as to 

 present scarcely any plane surface. Some 

 of these species are less common than 

 others, but there is scarcely a pond, canal, 

 or any large body of still water, which does 

 not contain some of them. In canals they 

 sometimes grow so profusely as to impede 

 navigation; and in autumn, when they shed 

 their leaves, the latter are liable to be car- 

 ried away by the current, and choke the 

 sluices of mills. The herbage and seeds 

 afford food to many water-birds and my- 

 riads of aquatic insects. French: Potamot; 

 German : Saamkraut. [C. A. J.] 



POTATO. A highly esteemed esculent 

 consisting of the tuber of Solanum tube- 

 rosum. — , CANADA. Helianthus tubero- 

 sus. —, MADAGASCAR. Solanum An- 

 gaivi. — , NATIVE, of Tasmania. Gas- 

 trodiasesamoid.es. — , SEASIDE. Ipomam 

 pes capree. — , SPANISH, or SWEET. 

 Batatas edulis. —, TEL1NGA. Amorpho- 

 phallus campanulatus, much cultivated in 

 India as an esculent. — , WILD. The 

 West Indian name for Ipomcea, 



