86 ECONOMIC WOODS OF THE UNITED STATES 



present in variable amount; often conspicuous. Resin ducts 

 absent. Gum ducts sometimes present in a few species. Rays 

 varying from minute to large and conspicuous. 



A Ring-porous Woods. Largest pores localized in a distinct 

 ring or band in early wood.* (For B, see p. 95.) 



a Late wood with radial lines or patches (frequently 

 branched or fan-like) composed of small pores and paren- 

 chyma, usually lighter colored than remainder of wood; 

 also with parenchyma in fine concentric lines, distinct to 

 indistinct.! (For b, see p. 88.) 



a 1 Rays all very fine, inconspicuous.! Woods soft to 

 moderately hard; stiff but not strong; sp. gr. .45-. 59. 



a 2 Pores in early wood few, small, nearly circular, open, 

 and rather widely separated in a single row. Color 

 of wood light brown or roseate. Odorless and taste- 

 less. Vessels without spirals; bordered pits circular, tending 

 to become scalariform in small vessels; perforations simple with 

 tendency to scalariform with few bars; pits into ray cells either 

 half-bordered or simple. Rays uniseriate (occasionally bise- 

 riate in median portion), 5-15 cells high; slightly heteroge- 

 neous. Western Chinquapin, Castanopsis chrysophylla 

 de C. (P). 



b 2 Pores in early wood very numerous, large, mostly 

 oval or elliptical, open, and in a broad zone. Color 

 of wood brown; stains blue-black in contact with 

 iron when moist. Odor of fresh wood mild but dis- 

 tinct. Taste somewhat astringent due to tannin 

 content. (Microscopic features given in preceding apply 

 here.) Chestnut,§ Castanea detitata Borkh. (C, N). 29 



* This feature may be obscure in very narrow growth rings where the pro- 

 portion of late wood is so reduced that the wood appears diffuse-porous. 



t The visibility of wood parenchyma is usually increased by moistening 

 the smoothly cut end of the specimen. 



t The distinctness of the rays refers to the cross section unless otherwise 

 stated. 



§ The chinquapin chestnut (Caxlaiica pumila Mill.) is a small southern tree 

 of only local importance for fence posts and fuel. . The wood is mostly harder, 

 heavier and of slower growth than the other species. The structures of the 

 two woods are nearly identical. 



