2758 



POPULUS 



POPULUS 



placentae 2. Eu., Siberia. The tree usually has a pyram- 

 idal habit of growth and a dark cast to the foliage. 

 It is a less lustrous tree than the cottonwood and grows 

 more slowly. Var. betulifdlia, Torr. (P. betulifolia, 

 Pursh. P. hudsonica, Michx. P. nigra var. hudsonica, 

 Schneid.), has the young growth and the petioles downy. 

 B.M. 8298. Specimens of this plant were found along 

 the Hudson by Michaux, who thought it an American 

 species and published it early in the century as Populus 

 hudsonica. Pursh, in 1814, published it again as the 

 "birch-leaved poplar," Populus betulifolia, from trees 

 found near Lake Ontario. Although it was found half 

 wild in N. Y. about a century ago, it does not appear 

 to have increased itself in Amer., and the variety is 

 probably of European origin. P. nigra is rarely seen, 

 even in cult, grounds. It is sometimes spontaneous in 

 the E. Variable in cult, and grown in European col- 

 lections under a variety of names. With the exception 

 of var. italica, these forms are little known in this 

 country. P. vistulensis, Dode, is a form of moderately 

 strong growth; branches spreading: Ivs. rhomboidal, 

 dark green. The two main forms or types of the black 

 poplar are the glabrous or smooth (var. typica, Schneid.), 

 S. Eu., and the pubescent (var. betulifolia). The Eng- 

 lish or downy black poplar makes a wide-spreading 

 attractive large tree, and forms great burs on its trunk. 

 Var. elegans, Bailey (P. elegans of nurserymen, and 

 probably some one of the well-known European forms), 

 is a tree of pronounced strict or pyramidal habit, but 

 considerably broader than the Lombardy poplar, with 

 thinly pubescent twigs and petioles: foliage small and 

 light-colored and very versatile in a breeze, with a 

 handsome reddish tint to the If.-stalks and young 

 shoots. It is worth growing in every well-kept place, 

 especially if placed against a planting of heavier foliage. 

 Populus canescens of some American nurserymen (not 

 of botanists) is very like this, although it has less color 

 and brightness. P. charkowiensis, Schroed., is probably a 

 hybrid in this group, by some supposed to be Lombardy 

 poplarxP. nigra; apparently allied to P. Eugenei. Var. 

 Viadri, Aschers. & Graebn. Tree narrow-pyramidal 

 with ascending branches: Ivs. like those of P. nigra but 

 more cuspidate. P. afghanica, Schneid. (P. nigra var. 

 afghdnica, Aitch. & Hemsl.), 

 of Afghanistan, has exceed- 

 ingly slender branches and 

 very small Ivs. Not in cult, 

 in this country. 



3133. An old clump of Lombardy poplar. 



3132. Populus nigra var. italica. 

 The Lombardy poplar. ( X Vz) 



Var. italica, Du Roi (var. pyramiddlis, Spach. P. 

 italica, Moench. P. dilatdta, Ait. P. fastigidta, Poir. 

 P. pyramiddlis, Borkh. P. pyramiddta, Moench. P. 

 sinensis, Dode). LOMBARDY or ITALIAN POPLAR. Figs. 

 3132, 3133. Differs from the typical black poplar 

 (P. nigra) in its tall narrow growth, glabrous young 

 shoots, a confirmed habit of suckering from the root 

 and generally a more tapering base to the Ivs. : buds 

 small: lower 

 branches of the 

 head taking a 

 strong upward 

 direction so that 

 it has no hang- 

 ing or drooping 

 spray; holds its 

 green foliage late 

 in autumn. It 

 is a staminate 

 sport from P. 

 nigra var. typica, 

 originating in 

 the plains of 

 Lombardy about 

 1700-20 and now 

 widely spread 

 over the world 

 by means of cut- 

 tings. Pistillate 

 Lombardies 

 have been re- 

 ported but they 

 are of different 

 origin and are usually broader-headed trees. With 

 age, the Lombardy poplar becomes one of the most 

 striking and picturesque trees, particularly when some 

 of the sprouts are allowed to grow about the old 

 stock, as in Fig. 3133. In the northernmost states it 

 is not long-lived. P. thevestma, Dode, from Morocco, 

 is apparently a form of the Lombardy poplar type 

 with whitish or gray bark: tree very large: Ivs. very 

 large, almost triangular, toothed, shining, with carmine 

 petioles. 



.Var. plantierensis, Schneid. (P. plantierensis, Dode). 

 Similar to Lombardy poplar but with reddish pubescent 

 petioles and short-pubescent branchlets. Of horticul- 

 tural origin, in the nursery of Simon-Louis at Plantieres, 

 near Metz, France. This is the fastigiate form of P. 

 nigra var. betulifolia; probably not in commerce in this 

 country. Both sexes are known. 



AA. Lf. -margins more or less distinctly ciliate. 



9. Frem6ntii, Wats. WESTERN COTTONWOOD. Large 

 tree with trunk sometimes 5-6 ft. diam., very large 

 head of stout spreading somewhat pendulous branches, 

 and bark on mature trunks deeply and broadly 

 ridged: Ivs. deltoid or roundish (on young shoots 

 reniform or rhombic), broader than long, with a broad 

 acute apex or sometimes even rounded at apex, 

 cuneate or truncate at base, coarsely irregularly ser- 

 rate with incurved gland-tipped teeth, thick, firm and 

 shining at maturity, 2-3 in. long; petiole to 2H in. 

 long and often pubescent; glands absent at base of If.: 

 catkins lJ^-4 in. long, the pistillate fls. on short pedi- 

 cels and with thin brown filiform-lobed scales; stamens 

 50-70: caps, ovate, to 1J^ in. long. Banks of streams. 

 W. Texas, S. Colo., Utah, Nev., Calif. S.S. 9:496. 



^ 10. Wislizenii, Sarg. (P. Fremontii var. (?) Wisli- 

 zenii, Wats.). VALLEY COTTONWOOD of the Rio Grande 

 Valley, W. Texas, New Mex., and adjacent parts of 

 Mex., differing in having slender-pedicelled pistillate 

 fls. : Ivs. deltoid, sharply acuminate, truncate or slightly 

 cuneate at base: pistillate catkins very slender (2-6 in. 

 long). S.S. 14:732. A similar tree of Mex., where it is 

 also often planted for shade (and to be looked for in 



