4 BULLETIN 1007, U. S. DEPARTMENT OF AGRICULTURE. 



Table 2. — Properties of yellow poplar, cottonwood, and white pine compared with 

 basswood. Basswood— 100. 





Weight. 



Shrinkage from 



green to oven-dry 



condition. 



Strength at 12 

 per cent mois- 

 ture. 



Composite values. 



Species. 



Oven- 

 dry 



(spe- 

 cific 

 grav- 

 ity.) 



Air- 

 dry. 



Green 



In vol- 

 ume. 



Ra- 

 dial. 



Tan- 

 gen- 

 tial. 



Mod- 

 ulus 



of 

 rup- 

 ture 



in 

 bend 

 ing. 



Compres- 

 sion par- 

 allel to 

 grain 

 (maxi- 

 mum 

 crushing 

 strength). 



Strength 



as a beam 



or post. 



Hard- 

 ness. 



Shock- 

 resist- 

 ing 

 ability 



Stiff- 

 ness. 



Yellow poplar.. 



Cottonwood 



White pine. . . 



112 

 112 

 109 



104 

 108 

 104 



93 

 120 

 95 



72 

 89 

 49 



62 

 59 

 33 



74 

 99 

 63 



105 

 96 

 102 



Ill 

 105 

 119 



114 

 102 

 116 



128 

 119 



128 



103 

 134 

 109 



116 

 98 

 100 



Basswood is rated low in durability. The estimated average life 

 of untreated basswood lumber, under conditions subjecting it to 

 decay but not to mechanical wear, is placed at from 3 to 5 years. 

 Its length of life in any particular case may, of course, vary from 

 this, depending on conditions. If properly treated with coal tar 

 creosote, or some other standard preservative, its durability may be 

 greatly increased. 1 



STRUCTURE. 



Basswood is a diffuse-porous wood (PL I). The pores are about 

 uniform in size and quite evenly distributed throughout the annual- 

 growth ring. They are, however, somewhat less numerous near the 

 outer limits of each annual ring, and this makes a contrast with the 

 greater number of pores at the beginning of each ring so that the 

 growth rings can be quite readily distinguished on a smoothly cut 

 transverse section. Medullary rays are generally not conspicuous on 

 longitudinal surfaces; in some pieces, however, they are reddish and 

 quite conspicuous on a quarter-cut surface; on a smoothly cut trans- 

 verse section they can be readily distinguished without the aid of a 

 lens. 



IDENTIFICATION. 



In appearance basswood resembles somewhat yellow poplar, 

 cottonwood, buckeye, and tupelo. The yellow poplar, how r ever, can 

 be distinguished by its yellowish-brown heartwood, which has a 

 characteristic greenish tinge. In cottonwood the medullary rays 

 are very fine and barely visible even with a hand lens on a smoothly 

 cut transverse surface, in contrast to those in basswood, which are 

 visible to the unaided eye; the pores of cottonw T ood are conspicuously 

 larger than those of basswood, as seen under a hand lens, and cotton- 

 wood generally has a "woolly" texture on sawed surfaces. In 

 buckeye and tupelo the rays are also finer than in basswood. The 

 brownish-black, longitudinal streaks occasionally found in the heart- 

 wood help to distinguish basswood. 



1 Farmers' Bulletin 744, Preservation of Farm timbers, gives methods of treatment. 



