POPULUS 



POPULUS 



2757 



Maxim. (P. tremula var. adendpoda, Burkill. P. Sil- 

 vestrii, Pampan.), is a recent Cent. Chinese species 

 (allied to P. tremula) not in the trade : Ivs. long-stalked, 

 broad-ovate, long-acuminate, serrate, soft-pubescent at 

 least on young trees, those on old mature trees closoly 

 crenate, greenish beneath. It is growing at the Arnold 

 Arboretum and in the Rochester parks, where it is 

 doing well. 



5. grandidentata, Michx. LARGE-TOOTHED ASPEN. 

 Tall straight tree, becoming 75 ft. high, with brittle 

 wood and dull gray bark which with age is marked 

 by plates but scarcely by ridges: Ivs. roundish ovate, 

 at the apex blunt or gradually narrowed and acute, 

 with large irregular sinuate teeth, white-woolly when 

 young but becoming glabrous: catkin-scales 5-6-di- 

 vided: fr. slender, long-pedicelled. Distinguished from 

 P. tremula by much larger and thicker Ivs., which 

 are bluish or rusty white beneath, more ovate in out- 

 line, with larger and more spreading teeth, stouter 

 If.-stalks and larger If.-buds. Nova Scotia to Minn., 

 Tenn., and X. C. S.S. 9:488. The If. -form is variable 

 and botanical varieties have been made from them. 

 In its normal or erect form it is rarely cult., but the 

 weeping kinds, under a variety of names, are frequently 

 seen. Most, and perhaps all, of these varieties origina- 

 ted in Eu., where the tree, like the cottonwood and the 

 common aspen, were early intro. The winter twigs of 

 the weeping varieties have a characteristic weak or 

 zigzag growth. These weeping forms are very likely 

 hybrids, sometimes distinguished as P. tremula var. 

 pseudograndidentata, Aschers. & Graebn. (P. pseudo- 

 grandiaentata, Dode). Fig. 3128. Buds at maturity 

 short, thick and somewhat viscid: Ivs. much like those 

 of P. tremula but larger, 3-4 in. diam., thicker, the 

 margin with cartilaginous edge at maturity. The 

 forms known as P. grseca pendula and Parasol de St. 

 Julien are by some referred to P. tremuloides, but these 

 names have been applied in this country at least to 

 plants of the above series. The P. gr&ca of authors is 

 confused. P. grandidentata is a common tree in the E. 

 U. S., growing under a variety of conditions, as on dry- 

 ish banks and slopes and near swamps and streams. 



6. tremuloides, Michx. AMERICAN ASPEN. Fig. 

 3129. Small weak tree, abundant northward and 

 springing up in clearings: Ivs. small, roundish ovate 

 with a slightly tapering or a truncate or sometimes even 

 a semi-cordate base, abruptly contracted to a short 

 usually apiculate point, finely crenate-serrate, downy 

 when j r oung but becoming smooth on both surfaces, the 

 petioles long and slender so that the foliage twinkles in 

 the slightest breeze : catkins drooping, with silky deeply 

 3-5-cleft scales or bracts, the pistillate becoming 3-4 

 in. long: caps, oblong-conical, not hairy or pubescent: 

 the species is very like P. tremula, but the Ivs. are 



3131. Populus Sieboldii. 



'* 

 3130. Staminate catkins of an aspen. ( X Ji) 



usually less circular and more abruptly acuminate, 

 the margins are small-crenate rather than deeply 

 toothed, and the Ivs. are green on the under side. 

 Generally distributed in N. Amer., north of Pa., and 

 Ky., and extending to Mex. in the mountains. S.S. 

 9:487. The bark of the young trees is whitish gray, 

 rendering the saplings very conspicuous in a coppice. 

 In woods the tree is said sometimes to reach a height 

 of 100 ft., but it is usually much smaller than this. 

 The far western form has 

 been separated as var. 

 aurea, Daniels (P. aurea, 

 Tidest.). Several If .-varie- 

 ties have been described. 

 Var. pendula, Schneid., is 

 a drooping or weeping 

 form. P. cercidiphylla, 

 Brit., is a form or a closely 

 related species in Wyom- 

 ing with small entire or 

 undulate Ivs. which bear 

 a peculiar concave gland 

 on the blade on either 

 side of the petiole attach- 

 ment. P. atheniensis is an 

 old name said to have 

 been given from a N. 

 American Athens, and as it 

 is a very early name it is used by Koch in place of P. 

 tremuloides. The P. graeca, of some authors perhaps 

 applies to this species through some error; see No. 5. 

 The name P. grseca appears to have originated with 

 Aiton, who apparently gave the name because he found 

 it cult, as the "Athenian poplar;" it is probably the 

 same as P. atheniensis, Ludw. 



7. Sieboldii, Miq. Fig. 3131. Tree, 20-30 ft., of 

 spreading habit, suckering freely, with rather dark and 

 heavy foliage: Ivs. large, round-ovate, with a short 

 triangular subacute apex, at the base truncate or 

 gradually narrowed into a short petiole, dentate-ser- 

 rate, with shallow glandular-incurved teeth, more or 

 less whitened beneath. Japan; the wood used for 

 matches and the tree less abundant than formerly. 

 Hardy in W. N. Y. Said by Wilson to be a tree of 

 medium size in Japan, very like P. tremula in general 

 appearance, and suckers freely. P. rotundifdlia, Griff. (P. 

 microcdrpa, Hook, f.), is very similar, but the Ivs. of old 

 branches are more or less cordate at base: Ivs. 3-4 in. 

 across, long-petioled, orbicular, sinuate : fruiting catkins 

 3-5 in. long and very slender, with a tomentose rachis : 

 caps, only J^in. long, with a very short pedicel. Him- 

 alaya region; probably not in cult, in this country. 

 P. rotundifolia var. Duclouxidna, Gombocz. (P. Due- 

 louxiana, Dode. P. macranthela, Lev.), of S. W. China, 

 has still longer fruiting catkins (6-10 in. long) and 

 longer-pedicelled caps. 



III. BLACK POPLARS AND COTTONWOODS. Lvs. not 

 lobed, mostly wider and broader-based than ovate in 

 form; mature Ivs. hard or firm in texture, green on 

 both surfaces, mostly with a clearly marked trans- 

 lucent or hyaline edge (which may appear as a thin 

 indurated line in the dried specimen); petiole com- 

 monly flattened, at least toward the blade: terminal 

 buds medium-large and more or less viscid, but not 

 markedly odorous: mostly large trees. 



A. Lf. -margins not dliate. 



8. nigra, Linn. BLACK POPLAR. Tree of medium to 

 large size, with smooth twigs and Ivs. somewhat 

 resembling those of the cottonwood, but generally 

 smaller and much less deeply toothed, longer in pro- 

 portion to then- width and often with a tapering or 

 rounded base, with no cilia or hairs on margin and no 

 basal glands; If .-stalk much flattened, so that the foliage 

 moves freely in the wind: stamens 12-25; stigmas and 



