Naturalisation in Extra-Tropical Countries. 417 



Populus balsamifera, Linn6. 



The Tacamahac- or Balsam-Poplar of the colder, but not the 

 coldest parts of North- America ; also in Siberia and on the Hima- 

 layan Mountains, where it ranges from 8,000 to 14,000 feet, called 

 by Dr. Kellog " the balmiest of all trees." It will endure the 

 winters of Norway to lat. 69 40' [Schuebeler]. It attains a height 

 of 80 feet. The tree may be lopped for cattle-fodder [Stewart and 

 Brandis]. Prof. Meehan says, that it will grow near the ocean's 

 brink. Its variety is P. candicans (Aiton), acknowledged as a dis- 

 tinct species by Wesmael. 



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



The Cottonwood-tree of North-America, extending to New 

 Mexico. Height to 150 feet ; stem to 8 feet in diameter. Not of 

 longevity ; needs full light ; adapted to a variety of soils, but 

 preferring such as is strong and humid [B. E. Fernow]. One of 

 the best poplars for the production of timber, which is soft, light, 

 very easy to work, suited for carving and turnery; it is durable if 

 kept dry, and does not readily take fire ; nevertheless it supplies a 

 fair fuel. The wooden polishing-wheels of glass-grinders are made 

 of horizontal sections of the whole stem, about one inch thick, as 

 from its softness the wood readily imbibes the polishing material. 

 It is useful for rails and boards, and has also come extensively into 

 use for paper-pulp. Judge Whitning says, that it has no rival in 

 quickness of growth among deciduous trees. Governor Furnas 

 found the stem-girth in Nebraska reaching to 93 inches in eleven 

 years at 2 feet above ground. Recommended by Wessely, together 

 with P. alba and P. nigra, for fixing drift-sand, on which these 

 poplars never become suffocated. It is advisable, to obtain cuttings 

 from male trees only, for planting along streets or near dwellings, 

 as the minute downy see^ls of the female trees are copiously wafted 

 through the air, and may have irritant effects on the respiratory 

 organs of the frequenting people. P. angustifolia (James) is 

 regarded by Wesmael as a mere variety of this species. 



Populus ciliata, Wallich. 



Himalaya, from 4,000 to 10,000 feet. Height as much as 70 feet, 

 with a straight trunk, which attains 10 feet in girth. 



Populus Euphratica, Olivier. 



From Algeria dispersed to the Himalayas and Songaria, up to 

 13,500 feet. Height to 50 feet. Dr. J. Aitchison measured 

 exceptionally big trees, their stems showing at 6 feet from the 

 ground a circumference of 9^ feet. Wood harder than that of 

 most poplars, the inner wood turning blackish in old trees. It is 

 used for planking and boat-building [Stewart and Brandis], also 

 for beams, rafters, boxes, panelling, turnery, but particularly on 

 account of its lightness for rafts. Cattle will browse on the leaves. 

 This is the Willow of the 137th Psalm [C. Koch]. 



