i8o2 The Trees of Great Britain and Ireland 



Its timber is used in house-building, and lasts well when protected from rain. A tree 

 5 ft. in girth sells for 12 to 26 shillings. 



4. Ybx. plantierensis, Schneider, Laubholzkunde, i. 803 (1906). 



Populus fastigiata plantierensis, Simon-Louis, Cat. 1884-1885, p. 51. 

 Populus plantierensis, Dode, in Mim. Soc. Hist. Nat. Autun, xviii. 43 (1905)- 



A fastigiate form of var. betulifolia, similar to the Lombardy poplar in habit 



and foliage, but with reddish pubescent petioles, and shortly pubescent branchlets. It 



originated in Simon-Louis's nursery at Planti^res, near Metz, whence it derives its 



name, and is said to occur in both sexes, and to be the result of a cross between the 



Lombardy poplar and var. betulifolia ; but this origin is unlikely. The original tree 



is a male, and when measured by Elwes in 1908 was 74 ft. by 5 ft. It is claimed 



for it that it is more vigorous than the ordinary fastigiate poplar, and not liable to 



die off at the top, as is frequent in the latter. There are specimens at Kew about 



25 ft. high, 



5. Var. viadri, Ascherson and Graebner, Syn. Mitteleurop. Flora, iv. 40 (1908). 



Populus viadri, Riidiger, in Abhand. Naturw. Ver. Reg. Bez. Frankfurt, viii. Mon. Mitt. 12 

 (1891); Koehne, in Verh. Bot. Ver. Brandenb. xxxvii. p. xxviii (1895), and in Gartenflora, 

 xxxix. 447 (1890). 



A narrow pyramidal tree, with ascending branches, which in branchlets, buds, 

 and foliage resembles the typical glabrous form of the species.^ It occurs along the 

 banks of the Oder, near Frankfort, whence it derives its name {Viadrus being the 

 Latin name for this river). It is said to produce pistillate flowers identical with those 

 oi P. nigra; but a tree ^ at Kew, about 25 ft. high, produced staminate flowers in 

 1 9 10. These differ slightly from the type in occasionally having peculiar scales 

 deeply bilobed at the summit. (A. H.) 



Distribution 



The distribution of the black poplar is very wide in Europe, but difficult to 

 define accurately, as it has been much planted in former times. In Norway and 

 Sweden, Schiibeler only knew it as a planted tree, and figured a very large one, 

 which from its burry trunk has the appearance of the English tree. This grew on 

 the banks of a river at Ronneby in Sweden ; and when measured in 1882 by Prof. 

 Wittrock, was, at four feet from the base, 34 ft. 8 in. in girth, dividing into two main 

 trunks a little higher up ; and this is the largest girth of which I have any record. 



In the Botanic Garden at St. Petersburg a tree, supposed to have been planted 

 by Peter the Great, measured in 1908 about 90 ft. high by 17 ft. in girth, forking low 

 down, and with a large burr on its trunk. 



In north Russia it extends to 57° N., according to Von Herder; but in the 

 St. Petersburg Herbarium I found a note by Kusnetsov stating that it was found at 



^ Koehne, who mentions trees of both sexes in Deut. Dend. 84 (1893), describes this peculiar poplar as a hybrid, P. 

 candicans x nigra, but he afterwards withdrew this very unlikely hypothesis. The leaves are more cuspidate at the apex than in 

 ordinary P. nigra, and it is possible that P. viadri is a hybrid, but I have seen no pistillate flowers. P. viadri appears to 

 have been introduced into cultivation by Spath, as it is mentioned as a novelty in his Catalogue, No. 91, p. 96 (1893-1894). 



2 Another tree at Kew, labelled P. viadri, also obtained from Riidiger, is different in habit, having spreading and not 

 ascending branches. It is pistillate, and appears to differ in no respect from P. nigra, var. typica. 



