LXVIIl. SALICA^CEJEI PO'PULUS. 821 



bracteas of the fertile flowers are, also, more deeply and regularly cut. The 

 branches are more upright and compact. The leaves are rounder, more 

 conspicuously 3-ribbed, and less deeply or acutely lobed ; not folded in the 

 bud, and without gum. They are downy beneath ; but the down is chiefly 

 greyish, and not so white or cottony as in P. alba : in some instances the 

 leaves are glabrous. (Smith.) A tree closely resembling the preceding 

 species, and found in similar situations. 



The wood of the white poplar weighs, when green, 58 Ib. 3 oz. per cubic 

 foot ; and in a dried state, 38 Ib. 7 oz. : it shrinks and cracks considerably in 

 drying, losing one quarter of its bulk. The wood of P. (a.) canescens is said 

 to be much harder and more durable than that of P. alba; in the same manner 

 as the wood of the Tilia europae'a parvifolia is finer-grained and harder than 

 that of T. e. grandifolia. The wood of both kinds is the whitest of the genus ; 

 and it is used, in France and Germany, for a variety of minor purposes, par- 

 ticularly when lightness, either of weight or colour, is thought desirable ; or 

 where an artificial colour is to be given by staining. It is excellent for form- 

 ing packing-cases, because nails may be driven into it without its splitting. It 

 is used by the turner and the cabinet-maker, and a great many toys and small 

 articles are made of it. The boards and rollers around which pieces of silk 

 are wrapped in merchants' warehouses and in shops are made of this wood, 

 which is peculiarly suitable for this purpose, from its lightness, which prevents 

 it much increasing the expense of carriage. The principal use of the wood of 

 the white poplar in Britain is for flooring^boards ; but for this purpose it 

 requires to be seasoned for two or three years before using. For the abele to 

 attain a large size, the soil in which it is planted should 

 be loamy, and near water ; though on a dry soil, where 

 the tree will grow slower, the timber will be finer-grained, 

 and more durable. In British nurseries, it is commonly 

 propagated by layers ; which, as they seldom ripen the 

 points of their shoots, or produce abundance of fibrous 

 roots the first season, ought to be transplanted into 

 nursery lines for at least one year before removal to 

 their final situation. The tree is admirably adapted for 

 thickening or filling up blanks in woods and plantations ; 

 and, for this purpose, truncheons may be planted 3 in. 

 or 4- in. in diameter, and 10ft. or 12 ft. high. Owing to 

 the softness of the wood, and its liability to shrink and 

 crack, it is dangerous to cut off very large branches j 

 and, even when branches of moderate size are cut off, 

 the wound ought always to be covered over with graft- * j3fH\ 

 ing clay, or some description of plaster, to exclude || '<& \ 

 the air. The tree is considered, both by French and i 4i ,3. p. ( a .) 

 English authors, as bearing lopping worse than any 

 other species of the genus ; and, when transplanted, the head should never 

 be cut off, and not even cut in, unless in cases where the tree is to be planted 

 in a hot and dry soil. 



X 3. P. TRE / MULA L. The trembling-/<?am/ Poplar, or Aspen. 



Identification. Lin. Sp. PL, 1464. ; Eng. Fl. t 4. p. 244. ; Hook. Fl. Scot, 289. 



Synonymes. P. llbyca Kaii Syn. 456. ; P. h^brida Dod. Pempt. 836. ; P. nlgra Trag. Hist. 1033. 



fig. ; P. pendula Du Roi ; Aspe ; le Tremble, Fr. ; la Tremola, Alberalla, Alberetto, Ital. ; 



Zitter-Pappel, Espe, Ger. 



Derivation. The English name of Aspen or Aspe is evidently derived from the German, espe. 

 The Sexes. Both sexes are described in the English Flora. 

 Engravings. Eng. Bot., t 1909. ; Hayne Abbild., t. 203. ; the plate in Arb. Brit., 1st edit., vol. vii. ; 



and our fig. 1494. 



Spec. Char., $c. Young branchlets hairy. Leaves having compressed foot- 

 stalks, and disks that are roundish-ovate, or nearly orbicular ; toothed in a 

 repand manner, downy when young, afterwards glabrous on both surfaces. 

 Stigmas 4, erect, eared at the base. (Smith.) A large tree, but seldom seen 

 so high as P. alba. Europe ; in rather moist woods. Height 50 ft. to 70 ft. 



3c 3 



