SALICACEAE. 



9 



POPULUS. Poplar. 

 (Family Salicaceae). 



Trees: deciduous. Bark at first 

 usually smooth and green or whit- 

 ish or orange, gray and often 

 deeply fissured in age. Wood rath- 

 er soft, white becoming brownish, 

 minutely diffused-porous with 

 fine medullary rays, satiny when 

 split. Twigs moderate, terete or 

 5-angled: pith rather small, 5-an- 

 gled, subcontinuous, brown. Buds 

 moderately small, ovoid or 

 elongated, appressed or sometimes 

 outcurved, sessile, solitary, with 

 several exposed scales of which 

 the lowermost is immediately over 

 the leaf-scar. Leaf-scars alter- 

 nate, somewhat raised, broadly 

 crescent - shaped to triangular, 

 somewhat 3-lobed, large: bundle- 

 traces 3, often compound: stipule- 

 scars narrow. 



The poplars possess many winter differences besides those 

 used in the present key. The bark is differently roughened: 

 in the native cottonwood gray and grooved between flat-topped 

 ridges, while in the commonly planted "Carolina cottonwood" 

 (XP. Eugenei), as in the Lombardy poplar which is one of 

 the parents of this, it is dark v/ith pale fissures between rather 

 sharp ridges. On young trunks, and the branches of older 

 trees, the smooth bark is colored in a characteristic fashion: 

 olive in the Lombardy poplar, orange in many "Carolina" 

 poplars, greenish-white in the large-toothed aspen, and some- 

 times almost chalky white in the silver poplar and our native 

 aspen. 



