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AMERICAN ASPEN. 

 Populus tremuloides, Michaux. 



FORM — A small tree usually 30-40 ft. high but may reach a height of 80 ft. with a diametei 

 of 20 inches. In Pennsylvania usually very small. Trunk continuous, tapering, bearing slender^ 

 brittle, and rather ascending lateral branches. Crown high, narrow, rather round-topped. 



BARK — On old trunks thick, deeply fissured and black; on upper portion of trunk and younj 

 stems yellowish-green to white, with dark blotches below the branches. Usually whiter at higl 

 altitude. 



TWIGS — Rather slender, reddish-brown, glossy, smooth, round, sometimes covered with a scalj 

 bloom; marked by reddish-yellow lenticels; roughened by leaf-scars; pith white and 5-angled. 



BUDS — Alternate, narrowly conical, sharp-pointed, smooth, shiny, usually appressed, oftet 

 incurved; covered by 6-7 reddish-brown, smooth, shiny, bud-scales; basal scale of lateral budi 

 outside. 



LEAVES — Alternate, simple, ovate to nearly round, cordate to truncate at base, acute a 

 apex, finely serrate on margin, 11-2 icches long, thin, dark green and shiny above, pale greei 

 below. Leaf-stalks laterally flattened. 



LEAF-SCARS — Alternate, large, conspicuous, lunate, with a cork-like surface; bundle-scar 

 3. simple or compounded. Stipule-scars linear, blackish, rather distinct. 



FLOWERS — Appear about April. Staminate and pistillate flowers occur on different trees 

 Staminate aments drooping, l|-2i inches long, bearing many closely packed individual flowei 

 with 6-12 stamens. Pistillate aments drooping, 11-21 inches long; when mature 4 inches long 

 bearing relatively few individual flowers with thick stigmas divided into thread-like lobes. 



FRUIT — An' oblong-conical capsule, 2-valved, light green, borne on a drooping stalk about 

 inches long. Seeds light brown, surrounded by a mat of long, soft, white hairs. 



WOOD — Diffuse-porous; medullary rays very fine and indistinct; pores very minute, invisibl 

 without a lens. Fine in texture, light brown to white in color, neither strong nor durabl 

 Weighs 25 lbs. per cubic foot. Used for paper pulp, boxes, jelly buckets, lard pails, spice keg 

 wooden dishes. 



DISTINGUISHING CHARACTERISTICS— The American Aspen, also known as Quaking Aspe 

 Trembling Aspen, Small-toothed Aspen, Popple, Poplar, and Aspen, may be distinguished ' 

 the round or ovate leaves which have a finely serrate margin and are short-pointed, 

 petioles of the leaves are decidedly flattened which causes them to tremble or flutter in respoi 

 to even a light breeze, whence the name Trembling Aspen. The alternate, sharp-pointed, conical 

 often incurved, closely appressed, shiny buds are also characteristic. The buds of the closel 

 related Larg^'-tcothed Aspen are stouter, not so sharp-pointed, usually divergent, and covere 

 with a flour-like, crusty, pale, woolly substance. The twigs are reddish and usually smooth whll 

 those of the Large-toothed Aspen are yellowish-brown often pale-downy or pale-scaly. The later 

 branches ar3 more ascending and the bark is lighter in color than that of the Large-toothe 

 Aspen. The bark is yellowish-green to white often marked with dark blotches. 



RANGE — A transcontinental species extending from Newfoundland to the Hudson Bay regio 

 and Alaska, south to Pennsylvania and along the mountains to Kentucky, west to 

 Rocky Mountains, Mexico, and California. The widest range of any species of tree in Nort 

 America. 



DISTRIBUTION IN PENNSYLVANIA— Found locally throughout the State. Most commo 

 in the mountainous part. 



HABITAT — Found upon practically all soil conditions except swamps. Prefers dry situationi 

 Common in abandoned fields, on cut-over areas and burns. Frequently mixed with Scrub Oa 

 which shades out in time. 



IMPORTANCE OF THE SPECIES — The* American Aspen is of no commercial importance 

 Pennsylvania. It remains too small and is too local in its distribution. Next to Spruce ai 

 Hemlock it is the principal pulpwood of the country. It is also beginning to be used f< 

 lumber. The wood is white and turns well. Ordinarily it is a poor competitor in the fore 

 but it does overcome the Scrub Oak upon burnt-over areas by shading it out. It is also valuab 

 as a temporary shelter species for other valuable trees. 



