96 



AMERICAN ASPEN. 

 Populus tremuloides, Michaux. 



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

 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 young 

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

 altitude. 



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

 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, often 

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

 outside. 



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

 apex, finely serrate on margin, 1J-2 inches long, thin, dark green and shiny above, pale green 

 below. Leaf-stalks laterally flattened. 



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

 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, 15-21 inches long, bearing many closely packed individual flowers 

 with 6-12 stamous. Pistillate aments drooping, 1J-2J 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 4 

 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, invisible 

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

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

 wooden dishes. 



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

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

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

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

 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 closely 

 related Larg^-toothed Aspen are stouter, not so sharp-pointed, usually divergent, and covered 

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

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

 branches ar2 more ascending and the bark is lighter in color than that of the Large-toothed 

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



RANGE A transcontinental species extending from Newfoundland to the Hudson Bay region 

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

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

 America. 



DISTRIBUTION IN PENNSYLVANIA Found locally throughout the State. Most common 

 in the mountainous part. 



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

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

 which shades out in time. 



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

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

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

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

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

 as a temporary shelter species for other valuable trees. 



