Populus 1795 



ridges. Young branchlets glabrous. Buds small, viscid. Leaves on old trees 

 deltoid, about 2^ in. broad, truncate at the base, and abruptly contracted at the apex 

 into broad short entire points: on young cultivated trees (Plate 409, Fig. 13), 

 reniform or rhombic, with a cuneate base and a similar apex ; serrations few, coarse, 

 with incurved points ; margin with dense minute cilia, discernible with a good lens ; 

 glands absent at the base ; petiole glabrous. 



Staminate catkins, 2 in. long ; axis glabrous ; disc broad, oblique, entire in 

 margin ; stamens sixty, with dark red anthers. Pistillate catkins, 2 in. long ; pedicels 

 short ; disc crenate, cup-shaped ; stigmas three, irregularly and crenately lobed. 

 Fruiting catkins, 4 to 5 in. long ; capsule thick-walled, three- to four-valved. 



This species grows on the banks of streams in California, Lower California, 

 Nevada, southern Utah, southern Colorado, and western Texas. 



It^ has only lately been introduced into cultivation, and small specimens may be 

 seen at Kew and Glasnevin. 



Var. WisHzeni, Watson, in Amer. Journ. Set. xv. 136 (1878). 



Populus Wislizeni, Sargent, Silva N. Amer. xiv. 71, t. 732 (1902), and Trees N. Amer. 165 (1905); 



Dode, in Mim. Soc. Hist. Nat. Autun, xviii. 39 (1905); Gombocz, in Math. Termes. KM. xxx. 



78 (1911)- 



This appears to have similar foliage, and is mainly distinguishable by the long 



pedicels of the flowers. It is the common poplar in the Rio Grande valley of western 



Texas and New Mexico, and the adjacent parts of Mexico. (A. H.) 



POPULUS NIGRA, Black Poplar 



Populus nigra, Linnaeus,^ Sp. PI. 1034 (1753); Loudon, Arb. et Frut. Brit. iii. 1652 (1838); 

 Wesmael, in De Candolle, Prod. xvi. 2, p. 327 (1868), and in Mim. Soc. Sc. Hainaut, iii. 258 

 (1869); Willkomm,/J?^j/'/«V,4ei%'/-a, 527 (1887); M&ihiexii, Flore Foresii^re, 491 (1897); Schneider, 

 Laubholzkunde, i. 5 (1904); Dode, in Mdm. Soc. Hist. Nat. Autun, xviii. ("groupe nigra") 37 

 (1905); Ascherson and Graebner, Syn. Mitteleurop. Fl. iv. 36 (1908); Gombocz, in Math. 

 Termes. Kdzl. xxx. 85 (19 11). 



A tree, attaining above 100 ft. in height and 20 ft. in girth, usually with a straight 

 and single stem, but occasionally dividing near the base into several limbs ; with wide- 

 spreading stout and irregular branches, not slender and regularly ascending as in 

 many of the hybrids. Bark deeply furrowed on old trunks, and often covered with 

 large burrs. In all its forms this species is readily distinguishable from the American 

 species and the hybrids by the leaves, non-ciliate on the margin, without glands at 

 the base, and when well-developed gradually tapering from the middle of the blade 

 to a long acuminate apex. 



The black poplar, and apparently all the poplars of the same section, rarely if 

 ever produce suckers while the trees are living, but if one is cut down suckers are 



* According to Dode, the trees introduced are var. Wislizeni; but until they flower their identification is uncertain. 

 However, Spath, Cat. No. 9S, p. 89 (1895-1896), states that the young plants first introduced in 1894 were obtained from 

 Colorado, where only the typical form of the species exists. 



'^ By this name Linnaeus meant the black poplar inhabiting temperate Europe ; though he quotes a Virginian poplar 

 ex Herb. Gronov. It is most convenient to assume, as the typical form of the species, the tree planted by Linnaeus at Upsala, 

 which is still living, and from which I gathered specimens in 1908. 



