1646 ARBORETUM AND FRUTICETUM. PART III. 
whether this is not also only a variety of P. trémula, though he has 
made it a species. The specimen is of a female. 
The above varieties, we suppose, still exist on the ramparts of Bre- 
men; cuttings of them might, no doubt, be procured through the 
Floetbeck Nursery. 
¥ P. t.8 péndula, P. péndula Lodd. Cat.,1836, and the plate of this variety 
in our last Volume, is the only distinct variety of P. trémula 
that exists in the neighbourhood of London. The handsomest 
specimen is at Kenwood, where a male plant, 8 years planted, is 
20 ft. high. : 
* P. t. 9 supina, P. supina Lodd. Cat., ed. 1836, closely resembles the 
preceding sort; and the plant in the Hackney arboretum is so very 
small, that it is difficult to say whether it is really distinct or not. 
¥ P.t. 10 levigata; P.levigata Ait. Hort. Kew., Lodd. Cat., ed. 1836 ; 
has shining leaves, rather larger than the species. 
Description. A rapid-growing tree, rather exceeding the middle size, with 
a straight clean trunk, tall in proportion to its thickness; and a smooth bark, 
which becomes grey, and cracks with age. The branches, which extend 
horizontally, and are not very numerous, become 
pendulous as the tree advances in age. The 
‘young shoots are tough, pliant, and of a reddish 
colour; and both the wood and the leaves vary ex- 
ceedingly, according to the dryness or moisture of 
the soil in which the tree is grown. The flowers 
appear in March, before those of any other poplar. 
The roots, Sir J. E. Smith observes, creep and emit 
suckers; and these, as well as the young branch- 
lets, are clothed with brown prominent hairs: they { 
are sometimes hoary, but not cottony. The colow § 
of the upper surface of the leaves is a fine dark ‘WRR 
glaucous shining green, and that of the under sur- 
face of a paler shade. The disk of the leaf has a 
small point, and 3 ribs; it is somewhat wavy, and 
often shorter than the footstalk; which, being vertically compressed in its upper 
part in relation to the plane of the leaf, counteracts the ordinary waving 
motion of the leaf in the wind, and causes it to quiver with the slightest 
breeze; whence has arisen the proverbial theme of comparison, the trembling 
of an aspen leaf. (Smith in Eng. Fl.) The leaves, says Dr. Johnston of Ber- 
wick, are of a fine smooth dark green, with a narrow yellowish edge, more or 
less fringed with soft hairs, and suspended on flattened stalks; so that 
“* When zephyrs wake, 
The aspen’s trembling leaves must shake :” 
and, by their friction on one another, they make a constant rustling noise. 
(Flora of Berwick upon Tweed, vol. i. p. 220.) The tree, when in a suitable 
soil, grows with great rapidity during the first thirty years after being planted, 
attaining, in that time, the height of from 60 ft. to 80 ft. ; afterwards, the trunk 
increases slowly in thickness, and in 60 o80 years it begins to decay, and can 
seldom occupy the ground profitably for a longer period. When cut over 
by the surface, the stool sends up shoots more freely than the white popiar, 
but much less so than most other trees that:stole. The want of shoots from 
the stools, however, is amply made up by the abundance of root suckers. 
Geography, History, §c. The trembling poplar is a native of most parts of 
Britain, in wet soils. Itis foundas far north as Sutherland; at above 1600 ft. 
above the level of the sea,in Braemar, in Aberdeenshire ; and, at an elevation * 
of 1500 ft., in the Isle of Mull. It is indigenous to Ireland, in the county of 
Dublin, and in other places mentioned in Mackay’s Flora Hibernica. It is 
found, according to Mirbel, in the whole of the south of Europe, Asia 
Minor, and Caucasus, and in Lapland to the Frozen Ocean. It is very abun- 
