Jan., 1905.] Key— Poplars in Winter Condition. 271 



KEY TO OHIO POPLARS IN THE WINTER CONDITION. 



John H. Schaffner. 



Populus L. Trees with light soft wood; the larger branches 

 usually with greenish-white, greenish, or brownish-gray bark. 

 Twigs with a terminal bud; buds more or less resinous but not 

 spicy-aromatic to the taste or smell; outer bud scales several, 

 glabrous, pubescent, or tomentose; leaf scars alternate, not 2- 

 ranked, more or less heart-shaped ; bundle scars 3; stipular scars 

 evident; self-pruning scars present and often very prominent; 

 bark bitter; pith 5-angled, sohd. 

 1. Twigs white or gray tomentose; buds ovoid-conical, short pointed. 2.. 



1. Twigs glabrous or pubescent, not tomentose. 4. 



2. Buds glabrous, or slightly pubescent or tomentose, resinous, large; 



twigs robust, usually angular; leaf scars large. 



P. heterophylla L. Swamp Poplar 



2. Buds tomentose or very pubescent, only slightly resinous, reddish- 



brown; twigs usually terete and slender; bark of larger branches 

 greenish-gray or greenish- white. 3. 



3. Buds very tomentose, small; twigs usually with abundant self-pruning- 



scars which heal very perfectly, showing a dark ring around a cen- 

 tral depression; bark often with black, diamond-shaped scars; 

 crown large, spreading, round-topped. P. alba L. White Poplar. 



3. Buds pubescent, not tomentose, rather large; bark of larger branches 



greenish-gray; trunk erect with an open, unsymmetrical straggling 

 crown; branches distant, small and crooked. 



P. grandidcntata Mx. Large-toothed Aspen. 



4. Terminal and lateral buds rounded or only slightly angular, rather 



short pointed, brown and polished or reddish-brown and pubescent ; 

 twigs usually slender and terete. 5. 



4. Terminal bud angular, large, rather long pointed; lateral buds long 



pointed or acuminate, sometimes angular. 6. 



5. Buds glabrous or nearly so, brown and polished; bark of larger 



branches smooth, light green. 



P. trcmnloides Mx. American Aspen 



5. Buds pubescent and reddish-brown; bark of larger branches smooth, 



greenish-gray. P. grandidcntata Mx. 



6. Tree spire-like, the branches nearly vertical; lateral buds acuminate, 



curved, ustxally spreading. 



P. dilatata Ait. Lombardy Poplar. 



6. Tree dome-shaped, the branches spreading. 7. 



7. Buds gummy resinous, reddish-brown and large; twigs often more or 



less pubescent, usually reddish, mostly terete. 



P balsamifera L. (Inc. var. candicans). Balsam Poplar 



7- Buds resinous but dry, greenish or yellowish-gray; lateral buds 

 acuminate, and usually curved and spreading; twigs glabrous, usu- 

 ally brownish-gray, often angled. P. dcltoides Marsh. Cottonwood.. 



mn 



