ECONOMIC WOODS OF THE UNITED STATES 89 



a 3 Rays very distinct. Color yellowish or gray. No 

 odor. Wood very coarse-textured; hard and 

 heavy; sp. gr. .65-80. Rays heterogeneous. Vessels 

 with spirals; perforations simple; pits into ray cells half- 

 bordered. Hackberry, Celtis occidentalis L. (C, N, S) ; 

 Sugarberry, C. mississippiensis Bosc. (S). 



b 3 Rays often obscure without lens. Color dark or 

 chocolate-brown. Odor suggesting licorice some- 

 times noticed. Wood coarse-textured, wooly; 

 straight-grained; hard and heavy; sp. gr. 65-80. 

 Rays homogeneous. Otherwise as in preceding. Slippery 

 or Red Elm, Ulmus pubescens Walt., or U. fulva 

 Michx. (C, N, S). 



b 2 Pores in early wood mostly in a single row; occasion- 

 ally more m wide growth rings. Rays not always dis- 

 tinct without lens. Woods without odor. (Microscopic 

 features as in preceding.) Elm. 33 



a 3 Pores in early wood rather large and distinct, 

 mostly open, forming a continuous row (Plate III, 

 Fig. 2), sometimes more than one row. Growth 

 rings often very uneven and widely variable in 

 thickness in different portions. Texture coarse 

 and wooly. Color light brown to gray or nearly 

 white. Wood very tough and difficult to split; 

 moderately hard and heavy; sp. gr. .60-.75. 

 White Elm, U. americana L. (C, N). 34 



b 3 Pores in early wood small to minute, mostly closed 

 with tyloses in heartwood; larger pores few and 

 rather widely separated in a band of small ones. 

 Growth rings fairly even and uniform. Texture 

 medium, not very wooly. Color light brown to 

 pinkish. Woods hard to very hard; heavy and 

 tough; sp gr. .70-.85. 



a 4 Bands of small pores in late wood rather few, 

 narrower than intervening spaces. Growth 

 rings distinct. Wood straight-grained, fairly 

 easy to split. Rock or Hickory Elm, U. 

 racemosa Thom., or U. thomasi Sarg. (C, N). 35 



