6 14 The yonrnal of Forestry. 



planted along the lines of the canals,^ for which position it is 

 peculiarly adapted by its upright habit, that is persistent even when 

 grown singly. 



15. FojjkIus Canadensis (Michaux), the Cotton- wood, is considered 

 by our excellent botanist Dr. Gray to be the P. monilifera of Aiton,* 

 and the same also as the P. loevigata of Willdenow. However, 

 Wood's .No. 5, P. monilifera, after Aiton also, seems to be different, 

 and he gives its habitat " on the Hudson near Troy, New York,"t 

 and quoting Dr. Beck, " ' apparently native.' " 



]\Iichaux found this species as far north as latitude 43o. It is abundant 

 in the Black Swamp of north-western Ohio, and fine trees may be seen 

 on the bank of the river below Detroit, Michigan. Michaux describes 

 the tree as larger than angidata, and the bark as thicker and 

 more deeply furrowed, having also a rounder head, and with the 

 boughs more numerously branched. This character of the outer 

 bark has attracted the attention of the fishermen on our great lakes, 

 who utilize it as a substitute for the more costly bark of the Qucrcus 

 sv.her, or cork. Sections of this substance, often three inches thick, 

 turned into oval form and perforated, are used as floats to their gill- 

 nets. 



Michaux reports this species rare on the Atlantic slope, but very 

 common in the Mississippi valley, especially above the mouth of the 

 Arkansas. 



The cotton- wood is the chief source of the steamboat fuel used on 

 our southern rivers. 



16. Pojmhis monilifei'a C Aiton), the Virginia or Swiss Poplar, does 

 not appear to have been found in this country by Michaux, father nor 

 son, but they say it is extensively cultivated in Europe, especially in 

 Switzerland and France ; though the males only are found there.* 



The young shoots of this species are angular. Comparing it with 

 the cotton-wood, M. FoucaultJ says the leaves are smaller and less 

 distinctly heart-shaped ; the young shoots and twigs are smaller and 

 less angular, becoming cylindrical in the third year, and the limbs are 

 less divergent^than those of the cotton-wood. It also grows faster, 

 and succeeds in drier soil, hence its popularity in France. The 

 wood is said to be softer than the cotton-wood of Michaux, or P. 

 Canadensis.^ 



Dr. Torrey found it in Western New York, on Lake Oneida and on 

 the Genoa river. ^ 



* Manual of Botany, Asa Gray, 2nd Edition, 18.56— his No. 4, page 419. 

 t Class Book, Alphonso Wood, 41st Edition, 185», page 507. 



:J: Imperial Director of Forests and Watercourses of France, quoted by Michaux as 

 the highest authority. North American Sylva, vol. ii., p. 120, 



§ This species is cited as P. monilifera, (Mrensch), by Sirmoni, in Lis Manual, p. 237. 

 H New Yoek Nat. History; Botany, vol. ii., p. 205. 



