256 SELECT PLANTS FOR INDUSTRIAL CULTURE 



pale, soft, and fissile. All poplars, like willows, are very im- 

 portant to eliminate miasma by absorbing humidity to an 

 enormous extent from stagnant swampy localities ; they are 

 likewise good scavengers of back-yards. 



Populus monilifera, Aiton. (P. Canadensis, Desfontaines.) 



The Cottonwood Tree of North America. Height 150 feet, 

 stem 4 feet in diameter. One of the best Poplars for the 

 production of timber, which is soft, light, easy to work, suited 

 for carving and turnery ; it is durable if kept dry, and does 

 not readily take fire. The wooden polishing-wheels of glass- 

 grinders are made of horizontal sections of the whole stem, 

 about one inch thick, as from its softness it readily imbibes 

 the polishing material. It is also useful for rails and boards, 

 and supplies a fair fuel. Judge Whitning says that it has no 

 rival in quickness of growth among deciduous trees. Recom- 

 mended by Wessely, together with P. alba and P. nigra, for 

 fixing drift sand, on which they never become suffocated. It is 

 recommended to obtain, for planting along streets or near 

 dwellings, cuttings from male trees only, as the minute downy 

 seeds of the female trees are copiously wafted through the air, 

 and have irritant effects on the respiratory organs. Of quick 

 and luxuriant growth, thriving even in arid and exposed 

 places. 



Populus nigra, Linne. 



The European Black Poplar, extending spontaneously to 

 China; in the Himalayas up to 12,500 feet. The spreading 

 variety one of the best of trees for lining roads. Wood similar 

 to that of P. alba. It includes P. dilatata (Ait.), or as a con- 

 tracted variety P. fastigiata (Desf.), the Lombardy Poplar. 

 Greatest height 150 feet. Growth rapid, like that of all other 

 Poplars. Wood soft, light, and of loose texture, used by join- 

 ers, coopers, and turners ; also for matches ; furnishing also 

 superior charcoal for gunpowder. Bark employed in tanning, 

 producing a fragrant leather ; it is, however, not rich in tannic 

 acid. The tree requires damp soil, It retains its foliage 

 longer than most Poplars. 



Populus tremula, Linne. 



The European Aspen. Height, 80 feet. It extends to Japan, 

 where also a peculiar species, P. Sieboldi (Miq.), exists. 

 The Aspen-wood is white and tender, and in use by coopers 

 and joiners. Like the wood of other Poplars, much sought 

 for paper-mills as an admixture to the pulp. 



