Populus l 777 



POPULUS ALBA, White Poplar 



Populus alba, Linnaeus, Sp. PI. 1034 (1753) ; Loudon, Arb. et Frut. Brit. iii. 1638 (1838) (in part) ; 

 Willkomm, Forstl. Fl. 516 (1887); Mathieu, Flore Forestiere, 483 (1897); Schneider, Laubholz- 

 kunde,\. 21 (1904); Ascherson and Graebner, Syn. Mitteleurop. Fl. iv. 17 (1908); Boissier, 

 Flora Orient, iv. 1193 ( l8 79) > Hooker, Fl. Brit. India, v. 638 (1888); Aigret, in Ann. Trav. 

 Publ. Belg. x. 1213 (1905); Gombocz, in Math. Termes. Kozl. xxx. 141 (191 1). 



Populus major, Miller, Diet. ed. viii. No. 4 (1768). 



Populus nivea, Willdenow, Berl. Baumz. 227 (1796). 



A tree, similar in size and bark to P. canescens. Young branchlets and buds 

 densely white tomentose. 1 Leaves (Plate 408, Fig. 1), very variable in size and shape, 

 dependent upon the position and vigour of the branchlets and on the age of the tree ; 

 on vigorous long shoots and suckers, large, up to 4 or 5 in. in diameter, ovate, 

 palmately three- to five-lobed ; lobes triangular, with deep sinuses ; margin ciliate with 

 minute glandular teeth ; subcordate at the rounded or broad base, acute at the apex ; 

 dark green and slightly tomentose above ; covered beneath with a dense snowy white 

 tomentum ; petiole rounded, tomentose. Leaves on short shoots (and occasionally at 

 the base of the long shoots), elongated oval, rounded at the base, with a few sinuate 

 teeth, usually covered beneath with a thin greyish tomentum ; in some cases (var. 

 denudata, Wesmael) glabrescent ; in some forms, broad and suborbicular like the 

 similarly placed leaves of P. canescens, but uniformly tomentose beneath, and with 

 fewer teeth in the margin ; petiole tomentose. 



Pistillate catkins similar to those of P. canescens, but more silvery in colour ; 

 scales obovate to lanceolate, with minute teeth, and fringed with long hairs ; stigmatic 

 lobes four, green, erect, long and linear, each of the two pairs united at the base. 

 Staminate catkins 2 (probably not perfectly developed), 1 inch long ; axis tomentose ; 

 scales concave, spatulate, dentate, fringed with long hairs; disc pubescent; stamens six. 



Spread over an immense area, P. alba is very variable in the form of the foliage, 

 and might be divided into several distinct geographical races ; but the wild specimens 

 in herbaria are scanty and incomplete ; and only a few important varieties will be here 

 mentioned. P. canescens, a native English tree, and P. tomentosa, wild in North 

 China, are easily distinguishable ; and are treated here as distinct species. 



1. Var. nivea, Aiton, Hort. Kew. iii. 405 (1789). 



This is the typical form 3 of the species described above. It has been long in 

 cultivation in western Europe, where it is known in gardens as var. argentea, var. 

 acerifolia, var. arembergiana, etc. It appears to be indigenous in eastern and south- 

 eastern Europe, in the Caucasus, in Persia, Turkestan, Afghanistan, and the Altai 

 Mountains, where specimens have been gathered by travellers. In Kashmir, accord- 

 ing to Mr. Lovegrove, of the Forest Department, from whom I have received 

 specimens, the typical form is fairly common in the wild state, attaining on an 

 average 90 ft. in height and 8 ft. in girth. 



In cultivated trees, the leaves are extraordinarily variable in size and shape, but it 



1 The suckers of/", alba are described by Dubard, in Ann. Sci. Nat. xvii. 163 (1903). 



2 The only male flowers of P. alba which I have been able to examine were produced by a small tree at Kew, labelled 

 var. nivea, and did not seem to be properly developed. Most, if not all, of the white poplars in Britain are female trees. 



3 Gombocz, op. cit. 148, 149, recognizes as forms of var. nivea, the slight variations, which are doubtfully constant, 

 called by Dode, op. cit. 21, 22, P. triloba, P. Treyviana, P. Palctskyana, P. heteroloba, P. Morisetiana, and P. palmata. 



