I 6 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



Both these species have well-marked geographical varieties, 

 there being a pubescent and a glabrous form of each. 



Populus nigra is the comprehensive name under which 

 Linnaeus included all forms of the European black poplar ; and 

 as the tree planted by his own hands at Upsala is of the 

 glabrous kind, we call this form Populus fiigra var. typica. 

 The glabrous variety appears to be strictly limited to southern 

 and south-eastern Europe, being widely spread in southern 

 Germany, Italy, Austro-Hungary, Balkan States, and southern 

 Russia. It is rarely seen in cultivation in this country. Its 

 natural habitat is the alluvial lands bordering on great rivers, 

 like the Danube and its tributaries, and the Po and Volga. 



The pubescent variety, Populus ?iigra var. betulifolia, has 

 dense, short pubescence on its orange-yellow twigs, readily seen 

 with a lens. It is apparently wild in southern England and 

 throughout France, where I have seen it from Picardy and 

 Normandy to the foot of the Pyrenees. ^ It is remarkable that 

 while well known to the pre-Linnaean English botanists, whose 

 numerous specimens may be seen in the British Museum, it 

 first received a distinctive name- from Michaux, who saw a few 

 trees in New York city and on the banks of the Hudson near 

 Albany, evidently introduced from England. It has not spread 

 in the United States, though it is said to be sold by nurserymen 

 there under the name Populus elegans. The English or pubescent 

 black poplar usually forms remarkable burrs on its trunk, and is 

 a wide-spreading, graceful tree, the habit of which is shown in 

 Fig. I, from a tree growing near Bishop's Stortford. It attains 

 an enormous size — one of the largest, which was cut down in 

 1 91 2 at West Stow, near Bury St Edmunds, being 92 feet in 

 height, and 19 feet in girth at 5 feet above the ground. This 

 was a planted tree, as the original set, about 4 inches in 

 diameter, was recognisable in the centre of the butt, being 

 separated from the exterior wood by a ring-shake. Near the 

 base 225 annual rings were counted. The timber was quite 

 sound, the first length measuring 39 feet by 44^^ inches quarter- 

 girth, or 536 cubic feet, the total contents being 748 cubic feet. 

 This species, being a native tree, occurs in both sexes; and 

 seedlings that were raised in June, 1907, from seed of a tree at 



^ There are two fine trees at Lourdes on the side of the river opposite the 

 shrine. 



- Populus huJsotiica, F. A. Michaux (i8[3). 



