POLYSTICHUM. 



THE ENGLISH FLOWER GARDEN. 



763 



best in peat, loam, and sharp sand, with 

 some broken lumps of sandstone, and 

 prefer a dry situation in the rock-garden, 

 or any situation which is not fuHy exposed 

 to the sun. A sHghtly shaded spot should 

 be selected, where they might be planted 

 among flowering plants suitable for the 

 same treatment and affording the needed 

 shelter. P. Robertianum (Limestone Poly- 

 pody) is a beautiful deciduous species, 

 somewhat difficult to manage ; it should 



Oak Fern (Polypcdium dryopteris). 



have a dry sheltered position, does not 

 mind sunshine, and prefers a mixture of 

 sandy and fibry loam, with a plentiful 

 addition of pounded limestone. P. alpesi7-e 

 resembles the Lady Fern, with fronds dark 

 green, and sometimes exceeding 2 ft. in 

 length. It may with advantage be grouped 

 with Lady Ferns, as it flourishes under 

 similar treatment. P. hexagonoptertnn 

 a native of N. America, is hardy in shel- 

 tered positions, and has elegant tapering 

 dark green fronds about i ft. in height. 



Polystichum. See Aspidium. 



PONTEDERIA {Pickerel Weed).- P. 

 cordata is one of the handsomest water- 

 plants, combining grace of habit and leaf 

 with beauty of flower. It forms thick tufts 

 of almost arrow-shaped, long-stalked 

 leaves, from i^ to over 2 ft. high, crowned 

 with spikes of blue flowers. P. a7Jgusti- 

 folia has narrower leaves. Both should 

 be planted in shallow pools of water. 



Division of tufts at any season. North 

 America. 



POPULUS (P^//^?;-)-— Usually forest 

 trees of northern and temperate countries, 

 often of rapid growth, mostly hardy in 

 our country, some giving very fine effects 

 in the landscape, and others of value in 

 woodlands. Generally they are much 

 neglected in country places, and in future 

 they will be worth more attention, not 

 only because their rapid growth often 

 helps to shut out objectionable things, 

 but some for their timber. Among the 

 best are the white, or the Abele Poplar 

 {P. alba)., and its variety Bolleana nivea, 

 which is whiter in the foliage than the 

 wild tree ; the great P. monilifera of 

 North America, grown under various 

 names in our gardens, and the most rapid 

 grower of Poplars ; the Balsam Poplar 

 {P. balsamifera) ; Fremont's Poplar {P. 

 Freinoiiti) ; P. grandidentaia ; P. hetero- 

 phylla of North America, of which there 

 is a pendulous variety ; P. laurifolia of 

 Siberia ; the Black Poplar {P. nigra), a 

 native tree which has one or two 

 varieties, one the Lombardy Poplar ; 

 P. Sieboldi of Japan ; P. Simoni of 

 China ; P. suaveolens of North-West 

 India ; P. tremuloides of North America, 

 and P. tricJwcarpa. Poplars being com- 

 mon in French and Continental gardens 

 generally, their culture has led to what 

 are called improved races and hybrids, 

 among which the variety Et/getiie is a 

 favourite in the east of France. Few 

 Poplars are ever planted in a fine way in 

 our country, and some of them are not 

 well known yet ; but such as are known 

 are very fine in habit, especially the Abele 

 and its allies, and there is no more beau- 

 tiful tree than our native Aspen {P. 

 treimtla), with its cloud of delicate mov- 

 ing leaves. 



Four kinds of Poplar are considered 

 natives of our country— the White Poplar, 

 sometimes growing 100 ft., the Grey 

 Poplar {P. caTiesccfrs), the Aspen, and 

 lastly, the Black Poplar, though this is 

 not certainly a native. In nature these 

 trees usually^ inhabit moist ground near 

 streams or lakes, or moist woods, and in 

 cultivation they often do best and look 

 best in such places, as in the Poplar-lined 

 valleys of France. In our moist climate, 

 however, such soil or place is by no means 

 essential to their growth, as we see noble 

 trees of the greater Poplars in good soil 

 away from lake or river ; but where there 

 is water it is often well to group them 

 near it, as, like the Willows, they are 

 rarely so good in effect as when grouped 

 near water. The Lombardy Poplar is 



