PRINCIPAL TREES. 69 



not to be confounded with the true white birch (Betula popuUfolia) 

 ■which does not seem to occur in this region and is a much inferiot 

 tree. The paper birch is the characteristic hardwood tree of the 

 fresher sandy soils, is always small, grows best in the northern coun- 

 ties, does not thrive on the poorer sandy "barrens," occasionally 

 forms small thickets, is generally mixed with pine and along Green 

 Bay with arborvitae. Like aspen, it enters extensively in the brush 

 cover of many cut-over bare lands, but thrives only where consider- 

 able sand is present in the soil. 



a. White elm {XJlmus americana) is a tall, long-shafted tree common 

 in all hardwood forests. 



b. Cork elm (Ulmus raoemosu), commonly called rook elm, replaces 

 to quite an extent the preceding species in many localities, and prob- 

 ably forms near 30 per cent, of all elm of the region. 



A "bastard" elm, vrith the foliage of white elm and the bark of cork 

 elm, is often noted by the woodsmen. 



c. Slippery elm {Ulmus puiescens) occurs sparingly in parts of this 

 region. 



4. MAPLE. 



a. Sugar maple (Ao&r saccharum) is a common tree Of all hardwood 

 forests, and, to a very considerable extent invades with aspen and 

 paper birch the regular pinery. Among the small, young growth of 

 most hardwood forests it predominates in number. 



b. Silver maple {Acer sacolMrinum), often called soft maple, is quite 

 generally distributed throughout the mixed forest, as is also the 



Eed maple {Acer rubrum). The bush maples, spiked and striped 

 maple {Aoer spicatum and Acer pennsylvanicum) form a considerable 

 part of the undergrowth in the mixed woods of the clay land. 



a. Eed oak {Quercus rubra) is the common timber oak of the region 

 and occurs in all counties, and on both sandy and clay soils, but is 

 abundant only in the western and southern counties, and makes a 

 good tree only on the heavier soils. 



b. White oak {Quercus alba) occurs quite abundantly in the south- 

 ern and southwestern counties, but is very scarce, in any form, in 

 the greater part of the region. This is also true of the 



c. Bur oak {Quercus macrocarpa) . In the north central and eastern 

 parts, in the upper Wisconsin, Menominee and Peshtigo basins the 

 scarlet oak {Quercus coecinea) is generally the only "scrub oak"; it is 

 scattered here over extensive tracts of sandy cut-over lands as a bushy 



