Proceedings of the Ohio State Academy of Science 123 



4. Leaves broadly ovate or suborbicular ; terminal winter buds rounded 



or only slightly angular. 7. 

 6. Trees of tall, narrow growth with strongly erect branches, giving a 

 spire-like appearance, young twigs glabrous ; leaves usually wider 

 than long, more or less acute at the base. P. dilatata. 



5. Trees with spreading branches. 6. 



6. Young leaves pubescent; capsules nearly sessile. P. nigra. 



6. Young leaves not pubescent, shining; capsules slender-pedicelled. P. 



deltoides. 



7. Leaves coarsely sinuate-dentate, densely white-tomentose when young, 



glabrous wdien mature. P. grandidentata. 

 7. Leaves crenulate-dentate, glabrous except the ciliate margins. P. 

 tremuloides. 



1. Populus alba L. White Poplar. A large tree with 

 smooth, light, greenish-gray bark often with black diamond- 

 shaped scars ; sprouting freely from the roots and hence not de- 

 sirable for yards. Young foliage densely white-tomentose, the 

 leaves becoming glabrate and dark green above, broadly ovate or 

 nearly orbicular in outline, 3-5 lobed, or irregularly dentate, 2-4 

 in. long. Native of Europe and Asia. Ohio. 



2. Populus heterophylla L. Swamp Poplar. An ir- 

 regularly branching tree with rough bark. Leaves long-petioled, 

 boardly ovate, crenulate-denticulate, 5-6 in. long. In swamps. 

 Conn, to Ga., west to La. and northward to Ark., Ind. and Ohio. 



3. Populus balsamifera L. Balsam Poplar. A large 

 tree with nearly smooth gray biark. Leaves broadly ovate, 

 dark green and shining above, pale beneath, rounded or acute 

 at the base, crenulate, 3-5 in. long. AVood very light and 

 soft. In moist or dry soil, commonly along streams and 

 lakes. The subspecies P. balsamifera candicans (Ait.) Gr. 

 Ealm-of-Gilead, has the leaves broadly ovate, truncate or 

 cordate at the base, and the petioles and nerves usually 

 puberulent. Mostly escaped from cultivation. Newf. to 

 Alaska, south to N. Y., Ohio, Neb., and Nev. 



4. Populus nigra L. Black Poplar. A large tree with 

 terete twigs. Mature leaves firm, broadly deltoid, abruptly ac- 

 uminate at the apex, broadly cuneate or obtuse at the base, cre- 

 nate, 2-4 in. long. Naturalized from Europe. N. Y. and south- 

 ward alone the Delaware R. 



