POPULUS 217 



being supplanted to a great extent by hybrids which have sprung up between 

 it and P. monilifera or P. angulata ; possessing a superior vigour, the latter 

 are favoured by planters. It is not easy to distinguish it always from its 

 hybrid progeny, but from the two American species just mentioned it is to be 

 recognised by the absence of marginal hairs and basal glands on the leaves. 

 The hybrids also have these characters in a greater or less degree. As a 

 timber-producing tree, P. nigra is not equal to P. serotina and P. marilandica, 

 which are discussed in their place, but as a tree for parks and gardens it has 

 advantages. It is more leafy, has a more compact and shapely habit, 

 branches more freely and finely, and it does not grow so rampantly. 



Var. BETULIFOLIA, Torrey (P. hudsonica, Mickaux). Downy Black 

 Poplar (Bot. Mag., t. 8298). A variety differing from the type in the 

 young shoots, leaf-stalks, midrib, and main flower-stalk being downy. The 

 tree, or rather its naming, has a curious history. It was first recognised by 

 Michaux early in the nineteenth century growing on the banks of the Hudson 

 River, near Albany, in New York State ; he thereupon named it P. hudsonica. 

 There is no doubt, however, that it is of European origin, and trees are known 

 to have existed in England in the eighteenth century. Indeed black poplars 

 with downy shoots, collected in England, are common in the older herbaria. 

 This variety, like the type, produces great burrs on the trunk, and up to its 

 middle age at least is a neat, densely branched, leafy tree, very much 

 superior to the gaunt rampant hybrids now almost exclusively planted. 



Var. ITALICA, Duroi (var. pyramidalis, Spach ; P. fastigiata, Desfontaines\ 

 Lombardy Poplar. This well known and beautiful tree, the most valuable 

 of all fastigiate trees, differs only from the type in its slender tapering form and 

 quite erect branches. Nearly all the Lombardy poplars in cultivation are 

 male, but a few female ones are known. There is one near Kew Palace over 

 50 ft. high, but it is not so slender as the common male tree. For this reason, 

 and still more because it litters the ground near with its cottony tufts at 

 seeding-time, it is much less desirable. As the Lombardy poplar is propa- 

 gated only by cuttings, the female tree must be of independent origin. The 

 male, which is occasionally 100 to 125 ft. high, is recorded to have been 

 brought to England from Turin by Lord Rochford in 1758, and according to 

 Loudon, one of the first importation existed at Purser's Cross in 1838. 



Var. PLANTIERENSIS, C. K, Schneider (P. plantierensis, Simon-Louis}. 

 Very similar in habit to the Lombardy poplar (scarcely so slender), this 

 differs from it in having slightly downy twigs and leaf-stalks. For this reason 

 it is considered to have sprung from var. betulifolia, perhaps crossed with the 

 Lombardy. It originated at Plantieres, near Metz, in the nursery of Messrs 

 Simon-Louis, who offer it in both sexes. It grows very well, but so far as I 

 can see has nothing to recommend it before the ordinary Lombardy poplar. 



Var. THEVESTINA (P. Thevestina, Dode\ This appears to be a form of 

 Lombardy poplar with a white bark, very striking as seen in Algeria, where 

 it has been abundantly planted on the outskirts of towns, to keep bark the 

 drifting sand. Female specimens collected in Algeria show the catkins to 

 be i to i i ins. long, the leaves triangular-ovate, with a broadly wedge-shaped 

 base, without glands ; the leaf-stalks and young shoots downy. It has been 

 introduced to Kew, and shows the fastigiate habit, but owing perhaps to 

 reasons of climate or insufficient age, the bark does not yet show the vivid 

 whiteness of Algerian trees. 



Var. VIADRI (P. viadri, Ruediger). A slender, rather erect form of nigra 

 (not so much so as the Lombardy poplar). Introduced to Kew in 1893. 



P. SEROTINA, Hartig. BLACK ITALIAN POPLAR. 



A large tree, always male, frequently over 100 ft. high, with an open, rather 

 gaunt habit, and extremely vigorous ; young shoots smooth, green, slightly 

 II P 



