POP ULUS 
1 1 
Young twigs hairy, more or less glabrescent. Stipules shorter than in var. genuina and in 
var. betuli/olia. Petioles hairy when young, longer than the laminae. Laminae triangular rather 
than rhomboidal in outline, truncate or even subcordate at the base, broader at the base than 
in the other varieties, less markedly acuminate, of a darker green as a rule than in the other 
varieties. Stamens about 12 to 16. 
Jersey (E. W. H.), Suffolk, Norfolk (Lindley, loc. cit.), Cambridgeshire. 
P. nigra is indigenous in England on rich alluvial soils where the water is not stagnant, 
by stream-sides, and near the upland margins of fens, chiefly in the lowlands of eastern England. 
It is impossible to state its precise range, owing partly to its having been confused with the 
black Italian poplar (p. 12), partly to the fact that British botanists when recording trees have 
rarely distinguished between indigenous and non-indigenous plants. Lines connecting Chelmsford, 
Gloucester, Shrewsbury, and Lincoln would probably include the great bulk of the area in which 
P. nigra is indigenous in England. Perhaps indigenous in southern Ireland. Not indigenous, 
and rare even as a planted tree, in Wales, northern England, and northern Ireland. Not reported 
from Scotland. 
Mid- western, central, and southern Europe ; northern Africa, Caucasus ; the Orient, central 
Asia to the Himalaya mountains; North America (not indigenous). 
*P. deltoidea x nigra var. betulifolia comb. nov. ; P. lloydii Henry in Trees of Great Britain 
and Ireland vii, 1830 (1913). 
leones : — Skan in Bot. Mag. t. 8298 — the parts from a pistillate tree — as P. nigra var. betulifolia. 
Differs from P. deltoidea in its young twigs and petioles being hairy, in its spring-leaves 
not being cordate or subcordate at the base, not or scarcely ciliate at the margin, and more 
acuminate at the apex. Differs from P. nigra var. betulifolia in many of its laminae being 
glandular at the junction of the petiole, in its summer-leaves being less acuminate, in its more 
numerous stamens, and in its pistillate catkins being rather more pendulous. Fruits not seen. 
Planted at Turnham Green, near London, in hedgerows in Hertfordshire, and doubtless elsewhere. The 
Turnham Green plant was shown to us by Mr A. B. Jackson, who supplied specimens from it for the pistillate 
parts of the illustration in Bot. Mag., loc. cit. 
*P. deltoidea x nigra var. genuina (see page 12); *P. italica x nigra var. genuina (see page 9). 
Series iv. *Delto/deae 
# DeltOldeae nobis; Virginiana Dode op. cit. 36 et 41 (1905). 
For characters, see page 9. 
[*P. deltoidea (see below). Laminae subcordate, slightly ciliate, suddenly acute. Stamens 
about 60.] 
x*P. serotina (p. 12). Laminae acute. Stamens about 20 — 30. Always staminate. 
x*P. canadensis (p. 12). Laminae acuminate. Capstiles subspherical. Always pistillate. 
[*POPULUS DELTOIDEA. Cotton-wood or Necklace Poplar. Plates 14; 15, 16] 
PopulllS deltoidea Marshall Arbust. Amer. 106 (1785); Sargent Silva N. Amer. ix, 179, 1896; P. vir- 
gimana Fougeroux in Mem. Agric. ( Soc . Roy. Paris ) for 1786, pt. i, 87 (1787); Ascherson und Graebner Syn. iv, 35 
(1908); P. monilifera Aiton Hort. Kew. iii, 406 (1789); Spach in Ann. Sci. Nat. ser. 2, xv, 32 (1841); Dode 
op. cit. 42 (1905). 
leones: — Watson Dendrol. Brit, ii, t. 5, as P. monilifera ; Sargent op. cit. t. 494. 
Camb. Brit. FI. ii (1913). Plate 14. (a) Long shoot. ( b ) Base of leaf (enlarged), upper side. ( c ) Margin 
of leaf (enlarged). Cambridge Botanic Garden (R. I. L.) 
Tree, attaining a height of about 30 — 35 m., sometimes with suckers. Bark smooth, greyish. 
Branches regular, curved, ascending. Winter-twigs subterete, glabrous. Winter-buds long and 
pointed, much longer than in P. nigra. Stipules larger than in P. nigra, about 8 mm. long, 
and 3 — 4 broad. Petioles about as long as the laminae, glabrous. Laminae tremulous, broadly 
ovate, more or less subcordate at the base ; margin subcartilaginous, ciliate especially when 
young, serrate with large hooked teeth ; apex suddenly acute. Catkins larger than in P. nigra ; 
2 — 2 
