PLANTS OF SOUTHERN NEW JERSEY. 391 



bb. Petioles strongly flattened. 



c. Leaves coarsely dentate. P. grandidentata, p. 392 



cc. Leaves finely crenulate-denticulate. P. tremuloides, p. 392 



aa. Bracts entire, leaves longer than broad. 

 b. Leaves pubescent beneath. 



c. Dull grayish, tomentous beneath. 



d. .Lincar-oblanceolate, 1-5 cm. long, crowded. Salix tristis, p. 394 

 dd. Oblanceolate or lanceolate, 5-15 cm. long, not crowdea. 



e. Petioles very short, young twigs less densely pubescent, 

 leaves averaging more regularly lanceolate. A frequent 

 species. 5". humilis, p. 394 



ee. Petioles longer, young twigs less densely pubescent, leaves 

 more frequently oblanceolate, a rare species in our range, 

 entering from the north. S. bebbiatia, p. 394 



cc. Lustrous and silky benetth. ,S*. sericea, p. 395 



e. Trees with inconspicuous greenish flowers in catkins or 

 panicles. 

 bb. Leaves glabrous beneath or glabrate. 

 c. Regularly, finely and closely serrate. 



d. With petiolar glands ; long acuminate. S. lucida, p. 395 



dd. Without glands. 



e. Stipules persistent. 



f. Leaves narrowly lanceolate ; long attenuate. 



5*. nigra, p. 392 

 ff. Leaves oblong lanceolate ; acuminate. S. cordata, p. 393 

 ee. Stipules deciduous. 



f. Leaves pale and glaucous beneath, usually very sparsely 



silvery silky. [5". fragilis]* 



ff. Leaves green beneath, perfectly glabrous, except very 



rarely along the midrib. S. nigra, p. 392 



cc. Irregularly or remotely serrate or toothed. 



d. Green beneath, remotely denticulate ; slender lanceolate. 



S. interior, p. 393 



dd. Glaucous beneath, irregularly crenate-serrate ; ovate or broadly 



lanceolate. 5". discolor, p. 394 



POPULUS L. 



Popuius heterophylla L. Swamp Poplar. 



Populus heterophylla Linnaeus, Sp. PI. 1034. 1753 [Virginia]. — Britten 227. 

 — Keller and Brown 115. 



Wet woods of the Middle district; very rare. Known from 

 one tree, found by Mr. Albert Commons, July 27, 1880, on 

 Fortesque Beach, and a small grove discovered by Mr. Bayard 



* Brittle Willow ; a common tree along streams in cultivated districts, 

 some other species of Willows are introduced about houses and occasionally 

 escape or persist where farms have been deserted. Notable among these is 

 the Weeping Willow {S. babylonica)- 



