414 THE CATKIN FAMILY. [ Populus. 
the scales of the leaf-buds often covered with a resinous varnish. Catkins 
cylindrical, usually silky-hairy, the scales irregularly toothed or lobed at 
the top. Perianth (or inner united scales) a small, flat, oblique cup. 
Stamens in the males from about 8 to near 30, with slender ‘filaments and 
small anthers. Ovary in the females 1- celled, with several ovules inserted 
on short, parietal placentas. Styles 2, with deeply forked stigmas. Fruit 
a capsule, opening in 2 valves. Seeds several, minute, with a tuft of long, 
silky hairs. 
A small genus, confined to the temperate regions of the northern hemi- 
sphere, very near the Willows in flowers and fruit, but distinct in habit 
and foliage, and in the presence of an apparent perianth, 
Under side of the leaves and young shoots very white and cottony. 1. P. alba. 
Under side of the leaves green and glabrous. 
Leaves ovate-triangular, tapering at the top, with small, regular 
teeth ° 3. P. nigra. 
Leaves small, orbicular or thomboidal, irregularly and rather 
coarsely toothed A : - . 2. P. tremula, 
The Tacamahac or balsam Poplar (P. balsamifera), the ce Poplar 
(P. angulata), and other North American species, are often planted. 
1, P. alba, Linn. (fig. 931). White Poplar, Abele.—_-A tall and hand- 
some tree, with a light-grey or ash-coloured bark, the young shoots, as well as 
the under side of the full-grown leaves, covered with a close, very white 
cotton. Leaves orbicular or very broadly ovate, irregularly sinuate or 
shortly lobed, more or less cordate at the base. Catkins sessile, about 2 
inches long, the membranous scales jagged at the top very deciduous, 
_ hairy in the males, less so in the females. Stamens usually about 8. 
Lobes of the stigmas linear. 
Along streams, and in open, moist woods, dispersed over central and 
southern Europe and temperate, Asia. In Britain, very generally planted, 
and probably also indigenous. 7, spring. P. canescens is a variety [or 
hybrid with P. tremula] with rather smaller leaves, seldom lobed, and 
not so white. 
2. P. tremula, Linn. (fig. 932). Aspen Poplar, Aspen.—A smaller 
tree than our two other Poplars, of slower growth, the branches more 
slender. Leaves nearly orbicular, like those of P. alba, but smaller, often 
not an inch broad, less deeply toothed, scarcely cordate, of a thinner tex- 
ture, without any white cotton, although sometimes very pale underneath ; 
the leafstalks particularly slender, so that the blade trembles with the 
slightest motion of the air. Catkins much smaller than in P, alba, the 
scales as well as the stigmas more deeply divided. Stamens usually 6 
to 8. 
In woods and forests, throughout Europe and Russian Asia, from the 
Mediterranean to the Arctic Circle, In Britain, apparently more frequent 
in Scotland and Ireland than in England. £7, early Spring. 
3, P.nigra, Linn. (fig. 933). Black Poplar.—A tall, quick-growing 
tree, readily assuming a somewhat pyramidal form, quite glabrous, with 
very glutinous buds. Leaves broadly rhomboidal or nearly triangular, 
tapering at the top, the lower angles rounded, the edge crenated or serrated, 
green on both sides. Catkins loose, about 2 inches long, the scales hairy 
only at the tips. Stamens more numerous than in P. alba and P. tremula, 
and the lobes of the stigmas shorter and broader. - 
