IO 
POPULUS 
leones: — Camb. Brit. FI. ii (1913). Plate 10. (e) Twig with pistillate catkins. (/) Pistillate flowers (en- 
larged). ( g ) Bracts of pistillate flowers (enlarged). (A) Leaf-bud (enlarged). Royal Gardens, Kew. 
Tree. Branches fastigiate, but less so than in P. italica. Laminae as in P. nigra. Pistillate 
catkins more drooping than in P. nigra, about 3 — 5 cm. long ; late March. Bracts laciniate, rather 
larger than in P. italica. Staminate trees not known. 
Planted, near Cambridge, and doubtless elsewhere ; but rare. 
Germany (planted). Perhaps of garden origin. 
5. POPULUS NIGRA. Black Poplar. Plates 11, 12, 13; 10, 15, 16 
Populus nigra Gerard Herb. 1301 ( 1 597) J Ray Syn. ed. 3, 446 (1724). 
Populus nigra L. Sp. PI. 1034(1753); Syme Eng. Bot. viii, 198 (1868); Ascherson und Graebner Syn. iv, 
36 (1908); Rouy Ft. France xii, 251 (1910). 
Tree, attaining a height of about 30 or 35 m., rarely with suckers. Root deep. Old bark black, 
thick, often with large corky excrescences. Twigs with brownish-yellow bark, terete or subterete. 
Winter-buds glabrous, shorter than in P. deltoidea. Laminae attenuate or truncate at the base, 
the lower ones of each twig acute to subacuminate, the upper ones narrower, smaller, and more 
acuminate. Catkins opening in April. Staminate catkins about 3 to 6 cm. long, drooping at 
maturity. Stamens about 8 to 16. Pistillate catkins peduncled, ascending or spreading, about 
6 or 7 cm. long. Bracts laciniate. Stigmas yellowish. Capsules ovate, ripening in May. 
(a) P. nigra var. genuina Wesmael in DC. Prodr. xvi, pt. ii, 328 (1868); P. nigra race typica Ascherson 
und Graebner Syn. iv, 39 (1908); P. nigra Rouy Ft. France xii, 251 (1910) in sensu stricto. 
Dode op. cit. pp. 50 — 53 (1905) has a number of “species” which conform to this var. genuina and which 
perhaps represent small varieties not distinguished in this country ; e.g., P. bisattenuata (“ espece douteuse ”), 
P. scythica, P. gallica, P. vistulensis, P. europaea, P. viadri, P. hypomelaena. 
leones : — Smith Eng. Bot. t. 1910, excluding the bracts of the enlarged flower, which should be glabrous. 
Exsiccata : — Fries, xii, 64, as P. nigra ; Schlaginweit, 370, as P. nigra. 
Young branches glabrous. Stipules narrowly triangular. Petioles glabrous, about as long as or 
shorter than the laminae. Laminae subdeltoid or subrhomboidal. Stamens about 8 to 12. 
This variety appears to be very rare in England. We have only seen it in Cambridgeshire, where 
the tree occurs rarely on the banks of streams. Whence the specimen was obtained from which the figure 
in Eng. Bot. was drawn, we have not been able to ascertain. The variety is cultivated in the University 
Botanical Garden at Cambridge. It is said to have the same distribution as the species. 
(b) P. nigra var. betulifolia Torrey FI. New York ii, 216 (1843); P. hudsonica Michaux fil. Hist. For. 
iii, 293, t. 10, 1 (1813); P. betulifolia Pursh FI. Amer. 619 (1814); Dode op. cit. 48 (1905); P. nigra race hudsonica 
Ascherson und Graebner Syn. iv, 39 (1908). 
leones : — The figure in Bot. Mag. t. 8298, purporting to be this variety is, at least so far as it was drawn 
from specimens from the pistillate tree at Turnham Green, P. deltoidea x nigra var. betulifolia (see p. 11). 
Camb. Brit. FI. ii (1913). Plate //. (a) Shoot in summer. ( b ) Base of young leaf (upper side). ( c ) The 
same (under side). Plate 12. (a) Winter-twig, (b) Twigs with staminate catkins. ( c ) Twigs with pistillate 
catkins. ( d ) Staminate flower and bracts (enlarged). ( e ) Pistillate flowers and bract (enlarged). (/) Leaf-bud 
(enlarged). Huntingdonshire (E. W. H.). 
[Exsiccata: — Todaro ( FI . Sic. Ex.) 1370, as P. nigra. This is an allied variety, P. nigra var. pubescens 
Parlatore FI. Ital. iv, 289 (1867) differing from var. betulifolia in having the laminae pubescent on both sides.] 
Young twigs hairy, at least when young. Stipules oblong. Petioles hairy when young, sometimes 
as long as or even longer than the lamina. Laminae usually rhomboidal, sometimes rather narrowly 
so, very acuminate. Stamens about 12. 
Essex, Suffolk, Cambridgeshire, Huntingdonshire, Bedfordshire, Gloucestershire, Herefordshire, Hertfordshire. 
Some of the trees in western Suffolk are very large and very old. 
Probably has nearly the same range as the species, though we have seen no foreign specimens ; North 
America (not indigenous). 
(c) P. nigra var. viridis Lindley Syn. 238 (1829)!; P. nigra Dode op. cit. 48 (1905) in sensu stricto; 
P. nigra race dodeana Ascherson und Graebner Syn. iv, 38 (1908). 
leones : — Camb. Brit. FI. ii (1913). Plate 13. (a) Long shoot, (b) Branch with short shoots. (A Base 
of leaf (enlarged), upper side. ( d ) Portion of leaf (enlarged). ( e ) Portion of young twig (enlarged). Cambridge- 
shire (C. E. M.). 
