Reproduction. Very prolific seeder; seeds annually from the 20th 

 year. Blossoms and sheds seed in spring and early summer. Germina- 

 tion percent low and vitality very transient (3 weeks). Seed very 

 minute, light, tufted; carried long distances by the wind. Exposed 

 mineral soil after a fire preferred as a seed bed. 



Range. Widest of all American trees, and is exceeded only by the 

 European aspen; Labrador to Alaska, and south to Mexico. Optimum, 

 western margin of Atlantic forest north of the 49th parallel. Sea-level 

 to 11,000 ft. (south Rockies). 



Climate. Variable; cool on the whole, since the zone rises as it 

 extends south. 



Soil. Inhabits wide range of soils but does well only on rather 

 fertile ones. 



Association. Occurs in pure stands with other poplars after fires; 

 balsam poplar, large tooth poplar, birches and spruces. It is nearly 

 always a transitory type, being supplanted by more tolerant species. 



General. Commercial importance is small (pulp and excelsior). 

 Very susceptible to fungous disease. Its chief importance lies in its ready 

 seeding of burned areas, which also explains its present abundance in 

 Canada. 



POPULUS GRANDIDENTATA, Michx. 

 Largetoothed Poplar. 



Size. Maximum 60 to 70 ft. by 2 ft. Average, 30 to 40 ft. 



Growth. Fairly rapid; not persistent. In Manitoba the average 

 age of 6 inch trees was 43 years, of 8 inch trees 60 years, and of 10 inch 

 trees 89 years. 



Root System. Heart. 



Bole. Medium taper. 



Crown. Moderately spreading. 



Tolerance. Intolerant. 



Wood. Light brown with thin light sapwood ; 28 pounds. 



Reproduction. Very prolific with annual seed years. Flowers 

 in April, and seeds ripen as the leaves unfold. Seeds minute and dark 

 brown; vitality very small. Prefers mineral soil. Seedlings hafdy. 



Range. Nova Scotia, New Brunswick, southern Quebec, and 

 Ontario; south and west to central Kentucky and Tennessee. Grows 

 at lower elevations, borders of swamps and streams. Optimum, in 

 southern part of range. 



Climate. Temperature medium; precipitation medium; humidity 

 medium. 



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