FOREST TREES. 187 



among the people in the country in the treatment of wounds, 

 bruises, rheumatism, and tumors. The name, "Tacamahac," 

 was given this tree on account of the resemblance of the bal- 

 samic coating of the buds to the genuine Tacamahaca, or res- 

 inous product of Fagara octandra. 



P. Fremont!, Watson. Fremont's Poplar. Leaves broadly tri- 

 angular, or somewhat kidney-shaped, with a broad, acute 

 point, with only a few serratures in each side. Leaf -stalks one 

 to two-and-a-half inches long. Fruiting catkins three or four 

 inches long; seeds small, white. A large tree, with gray, 

 cracked bark, that on the young branches yellowish. Twigs 

 round, smooth, not w r inged or angled. Along the Sacramento 

 River in California, and westward to Utah. Var. Wislizeni, 

 Watson, has sharply acuminate leaves, with very slender pistil- 

 late catkins, two to six inches long. This is the P. monilifera, 

 Torr., in Botany of the Mexican Boundary Survey, and found 

 further south than the species. 



P. grandidi'iitata, Michx. Large-toothed Aspen. Leaves three 

 to five inches long, roundish-ovate, with large, irregular, sinu- 

 ate teeth, and when young, densely covered with white, silky 

 wool, but becoming smooth on both sides. A large tree sixty 

 to eighty feet high, with rather smoothish gray bark. Wood 

 light and soft, and of late years used for paper pulp. Common 

 in the north, from Nova Scotia, Canadas, and the Northern 

 States, but rare southward except along the Alleghanies. 



P. heterophylla, L. Downy-leaved Poplar. Leaves heart- 

 shaped or roundish-ovate, with obtuse, incurved teeth ; white, 

 woolly when young, but becoming smooth, except on the ele- 

 vated veins beneath. Branches round. A large tree seventy 

 or eighty feet high, not common or very abundant. New Eng- 

 land to Illinois ; southward to Arkansas, and eastward to North 

 Carolina. 



P. monilifera, Ait. Cottonwood, Carolina Poplar. Twigs and 

 smaller branches thick, smooth, but sharply-angled or winged. 

 Leaves large, six to nine inches long, broadly heart-shaped, 

 smooth, sharply serrate, with slightly incurved teeth. Fertile 

 catkins very long, with scales finely fringed, but not hairy ; a 

 very large tree, often a hundred feet high, with stem four or 

 five feet in diameter. Wood soft, light, but burns rapidly 

 when seasoned, but gives out little heat. A common tree in 

 moist, low grounds, from New England to Colorado and Idaho, 



