ECONOMIC WOODS OF THE UNITED STATES 97 



a 4 Wood parenchyma conspicuous in few widely 

 separated lines, apparently terminating growth 

 rings; also about pores. " Ripple marks," when 

 present, readily visible to unaided eye; about 

 50 per inch. Rays fine but distinct. Pores 

 rather large, uniform in size and distribution, 

 solitary or in radial groups of 2-3; often filled 

 with dark red gum or with white deposits. 

 Gum ducts occasionally present in peripheral 

 row. Native wood hard and heavy; sp. gr. .73; 

 color rich reddish brown; often highly figured.* 

 Vessels without spirals; perforations simple; pits into 

 ray cells half-bordered. Rays 1-4 cells wide, few to 20 

 or more cells high; heterogeneous. Wood fibres often 

 finely septate; pits simple. Mahogany, Swietenia 

 mahagoni Jacq. (T). 46 



b 4 Wood parenchyma in numerous fine, wavy 

 lines. "Ripple marks" always present, uni- 

 form, invisible to unaided eye but distinct with 

 lens; about 250 per inch. Rays very fine, in- 

 distinct. Pores not large but distinct, variable 

 in size and distribution; solitary or in radial 

 groups of 2-3. Color dark yellowish brown 

 with greenish tinge, not uniform; becomes very 

 dark and oily in old trees. Wood with inter- 

 locked or criss-cross grain; extremely dense; sp. 

 gr. 1.14. Vessels without spirals; perforations simple; 

 pits into ray cells small, half -bordered. Rays uniseriate; 

 homogeneous; arranged in horizontal seriation. Wood 

 fibres not septate; pits bordered. Lignum-vitae, Guai- 

 acum sanctum L. (T). 



* The true mahogany is native to a region extending from the extreme 

 .southern part of Florida to the West Indies, and along the Gulf Coast in Mexico 

 from Tampico through Central America into the northern part of South 

 America. There is a wide variation in the properties of the wood from differ- 

 ent localities. That from Florida is like the hardest and heaviest of the West 

 Indian grades. Mexican mahogany is the most variable in quality, some of 

 it being light, soft and porous like Spanish cedar. There are many other 

 woods which appear on the market as mahogany. See Mell's "True Mahog- 

 any," Bui. No. 474, U. S. Dept. Agr., 1917. 



