102 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. 



Section II. Walls of traclieids of pith ray smooth, without dentate projections. 



a. One or two large pits to each tracheid on the radial walls of each cell of the pith ray. Group 3. /'. ttrolini,, 



lambertiiiiiu, and other true white pines. 



li. Three to six small pits on the radial walls of each cell of the pith ray. Group 4. /'. parri/ana, and other nut 

 pines, including also I'. balfouriana. 



II. RING-POROUS WOODS. 



[Some of Group 1> and cedar elm imperfectly ring-porous. 1 



A. Pores in the summer wood minute, scattered singly or in groups, or in short broken lines, the course of which is 

 never radial. 



1. Pith rays minute, scarcely distinct. 



a. Wood heavy and hard; pores in the summer wood not in clusters. 



'. Color of radial section not yellow -Is''. 



b'. Color of radial section light yellow ; by which, together with its hardness and weight, this species 



is easily recognized Osage oramje. 



1>. Wood light and soft; pores in the summer wood in clusters of 10 to 30 Catalpa. 



2. Pith rays very fine, yet distinct; pores in summer wood usually single or in short lines; color of heartwood 



reddish brown, of sapwood yellowish white ; peculiar odor on fresh section Sasxafrax. 



3. Pi tli rays fine, but distinct. 



a. Very heavy and hard ; heartwood yellowish brown Hlack lix-iml. 



I. Heavy; medium hard to hard. 



'. Pores in summer wood very minute, usually in small clusters of 3 to 8; heartwood light orange 

 brown .- Jitd mulberry. 



V . Pores in summer wood small to minute, usually isolated ; heartwood cherry red Coffee tree. 



4. Pith rays fine but very conspicuous, even without magnifier; color of heartwood red, of sapwood pale 



lemon Honey locust. 



Fia. 7 Wood of coffee tree. 



B. Pores of summer wood minute or small, in concentric wavy and sometimes branching lines, appearing as finely 



feathered hatchings on tangential section. 



1. Pith rays fine, but very distinct; color greenish white; heartwood absent or imperfectly developed. 



Haclclicrry. 



2. Pith rays indistinct; color of heartwood reddish brown, sapwood grayish to reddish white Elms. 



C. Pores of summer wood arranged in radial branching linos (when very crowded radial arrangement somewhat 



obscured). 



1. Pith rays very minute, hardly visible Chestnut. 



2. Pith rays very broad and conspicuous Oak. 



D. Pores of summer wood mostly but little smaller than those of the spring wood, isolated and scattered; very 



heavy and hard woods. The pores of the spring wood sometimes form but an imperfect zone. (Some diffuse- 

 porous woods of groups A and B may seem to belong here.) 



1. Fine concentric lines (not of pores) as distinct, or nearly so, as the very fine pith rays ; outer summer wood 



with a tinge of red, heartwood light reddish brown Hickory. 



2. Fine concentric lines, much finer than the pith rays; no reddish tinge in summer wood, sapwood white, 



heartwood blackish Persimmon. 



ADDITIONAL NOTES FOR DISTINCTIONS IN THK GROUP. 



Sassafras and mulberry may be confounded but for the greater weight and hardness and the absence of odor in 

 the mulberry; the radial section of mulberry also shows the pith rays conspicuously. 



Honey locust, coffee tree, and black locust are also very similar in appearance. The honey locust stands out by 

 the conspicuousness of the pith rays, especially on radial sections, on account of their height, while the black locust 

 is distinguished by the extremely great weight an dhardness, together with its darker browu color. 



