2764 



POPULUS 



POPULUS 



date or rounded and sharply glandular-crenate-dentate, 

 on the old branches broad-ovate or ovate-orbicular with 

 rounded or more or less cordate base and the margin 

 more or less distinctly glandular-dentate. Growing at 

 the Arnold Arboretum and the Rochester parks. P. 

 yunnanensis, Dode, is allied to P. szechuanica but is 

 insufficiently understood. 



3146. Leaves of Populus laurifolia 

 as illustrated in Ledebour's "Icones 

 Plantarum." (Reduced.) 



AA. Branchlets prevailingly with projecting narrow ridges. 



25. laurifdlia, Ledeb. (P. balsamifera var. laurifolia, 

 Wesm.). Fig. 3146. Tall tree with gray-brown bark 

 and smooth angled twigs: Ivs. ovate to ovate-oblong to 

 ovate-lanceolate or even narrower, acuminate, some- 

 times undulate, rounded at base, finely toothed and 

 somewhat ciliate, green above, more or less pubescent 

 on midrib at maturity, whitish beneath : stamens 20-30 ; 

 pistils sessile, 2-valved; staminate catkins about 3 in. 

 long, pistillate 4-5 in. Siberia. 



26. Lindleyana, Carr. (P. laurifolia var. mminalis, 

 Dipp.). Fig. 3144. Lvs. mostly willow-like, long-elliptic, 

 distinctly acuminate, or oval-elliptic on the older shoots, 

 roundish at base, with pubescent petioles, fls. and fr. 

 Perhaps a horticultural group, to which are probably to 

 be referred the garden names P. crispa (with more or 

 less crisped or crinkled margins), P. Dudleyi and P. 

 salicifolia. As seen in cult, in this country (and very 

 infrequent) it is a small or medium-sized tree, of slen- 

 der growth and with a somewhat weeping habit when 

 old. It is very like the native Populus fortissimo, but 

 is readily distinguished by its angled or furrowed sts., 

 and less tapering and crisped Ivs. which are conspicu- 

 ously finely reticulated and whitened beneath. The 

 color of its foliage is grayish green, and in this respect 

 it affords a contrast to the native species. P. fortissimo, 

 seems to be rather the better tree of the two, although 

 P. Lindleyana has a more striking appearance. The 

 botanical status of these trees is not clearly defined. 

 By some, P. Lindleyana is referred to P. laurifolia, but 

 the tree in cult, seems to be distinct. 



27. Simdnii, Carr. (P. laurifolia var. Simonii, Hegel. 

 P. balsamifera var. Simonii, Wesm. P. brevifolia, 

 Carr.). A strong strict tree, not large, with Ivs. differ- 

 ing from those of P. candicans in having a rounded 

 or tapering base and much finer teeth, but otherwise 

 they are somewhat alike: shoots reddish brown and 

 spotted, deeply grooved, somwhat drooping: Ivs. small, 

 mostly oval and tapering both ways, hanging on slender 

 petioles. Amoor Valley to China, where it is common. 

 G.W. 15, p. 246. Intro, into France about 1861 by 

 M. E. Simon, and somewhat planted in this country. 

 It has been planted as far north as Man. with entire 

 success. It is a very rapid grower, and is useful where 

 quick-growing windbreaks are desired. There are fasti- 

 giate and weeping forms. Shape of Ivs. variable, those 

 on vigorous shoots being round-obovate, acute-based, 

 and mostly rounded at apex. 



28. trichocarpa, Torr. & Gray. BLACK COTTONWOOD. 

 Very large tree, to 200 ft. and trunk to 8 ft. diam., 

 with wide head or top and upright branches: Ivs. 



varying from narrow- to broad-ovate, truncate or 

 cordate at base, acute or taper-pointed at apex, 

 finely serrate, to 8-10 in. long, shining green above 

 and rusty but becoming whitish beneath: catkins 2-5 

 in. long; stamens 40-60; pistillate catkins loose-fid., in 

 fr. becoming as much as 10 in. long; ovary 3-carpelled: 

 caps, nearly sessile. Calif, to Brit. Col. and Alaska, 

 reaching an elevation of 6,000 ft. S.S. 9:493. G.F. 

 5:281. Aside from the conifers, it is said to be the 

 largest tree in Ore. to Brit. Col. For P. hastata, see 

 No. 17. 



Following are supposed hybrids in the balsam poplar group: 



(a) P. berolinensis, Dipp. (P. certinensis, Dieck. P. pseudo- 

 balsami/era, Fisch.). Columnar tree supposed to be of hybrid 

 origin, with short ascending branches, the growths densely pubes- 

 cent and the young ones slightly winged but often becoming nearly 

 or quite smooth at maturity: buds greenish, pointed, viscid: Ivs. 

 on strong shoots 3-4 in. long, ovate or ovate-rhombic, mostly 

 rounded but sometimes cuneate at base, contracted into a long 

 glandular acuminate point, glabrous on both surfaces, greenish or 

 slightly whitish beneath, the margin not ciliate and with a very 

 narrow translucent edge visible under a strong lens, the margins 

 usually regularly crenate-serrate and sometimes with irregular 

 shallow lobes. Perhaps a hybrid between Lombardy poplar and P. 

 laurifolia. The name P. certinensis was applied to the staminate 

 plant. 



Whether the P. certinensis grown in N. Amer. (Fig. 3147) all 

 belongs with P. berolinensis is very doubtful. Some of it seems to 

 have many of the characters of P. deltoides. As grown in nurseries 

 and collections here, it is a very rapid-growing and hardy tree, with 

 a strong central leader and very heavy dense foliage ; differs from P. 

 monilifera as follows: Ivs. broad-ovate in outline, with a rounded or 

 tapering base and rather short point at the apex; the margin rather 

 closely-toothed, wavy; If. -stalk comparatively short, only moderately 

 flattened, glandless at the top; stipules present and conspicuous: bud 

 long; shoots slightly hairy. The foliage on the old wood or upon 

 slow-growing shoots is very unlike that upon the vigorous branches 

 and is almost identical with that of the balsam poplar, being broadly 

 oval, with finely serrate margins, and whitish beneath. The twigs, 

 also, are cylindrical. But the strong shoots are strongly angled or 

 grooved and the foliage is much like that of the native cottonwood, 

 but darker; and the growth is more close and erect. The sketch in 

 Fig. 3147 distinguishes the Ivs. The Certinensis poplar is a more 

 rugged tree than the cottonwood, with healthier foliage in the pres- 

 ence of If.-rust, and its wood is said to be valuable. It has been 

 much planted in the N. W., and deserves to be widely distributed. 

 Its effect in the landscape is considerably unlike that of the cotton- 

 wood. Its Ivs. stand out more homontally, while those of the 

 cottonwood hang loosely and often vertically and therefore give 

 the tree-top a heavier look. The terminal spray of the two is 

 particularly distinguishable in this regard. The Ivs. of Certinensis 

 upon the strong, erect shoots stand almost at right angles to the 

 shoot, and, at some distance, therefore, present only their ruffled 

 edges to the eye, producing a unique and picturesque effect. The 

 illustration (Fig. 3147) represents a top leaf of P. certinensis as 

 grown in this country, but the name may not be correctly placed. 



(6) P. Wobstii, Schroed. (P. Wobsky, Hort.?). Buds very viscid: 

 Ivs. 4H3 in. long and 2 in. broad, lanceolate, with widest part about 

 the middle, narrow but rounded at base, gradually tapering toward 

 the bluntly acuminate apex, slightly pubescent, white beneath, 

 ciliate and crenate-serrate; petiole with few scattered hairs: 

 branchlets glabrous. 



(c) P. Rasumow- 

 skyana, Schroed. 

 Buds pointed , 

 viscid: Ivs. on young 

 trees and vigorous 

 shoots 4x3 in., or- 

 bicular-o va t e, 

 rounded or sub- 

 cordate at base, con- 

 tracted above into a 

 gland-tipped acumi- 

 nate apex, very- 

 near 1 y glabrous, 

 pale beneath, the 



margin glandular- crenate and not ciliate; petiole terete, grooved 

 above: branchlets glabrous, ridged. P. Nolestii, as it has been 

 grown in this country, is either this form or very like it, but is little 

 understood. 



(d) P. Petrowskyana, Sehroed. Very like P. Rasumowskyana, but 

 with minute pubescence on branchlets and petioles; Ivs. on vigorous 

 shoots 5x4 in., ovate, cordate, the apex long-acuminate, pale 

 beneath; serrations deeper than in last. 



VI. VARIABLE-LEAVED POPLARS. Lvs. remarkably poly- 

 morphous or diverse on the same plant, from very 

 narrow to broad, coriaceous and reticulate, the peti- 

 ole more or less cylindrical, the buds little if at all 

 viscid: stamens few (about a dozen): caps, pedi- 

 cellate, elongated; stigmas 3. 

 29. euphratica, Oliver (P. diversifdlia, Schrenk. P. 



ariana and P. Litwinowiana, Dode) . Medium-sized tree, 



3147. Populus certinensis of American 

 plantations. (XM) 



