104 



KORKSTRY INVESTIGATIONS U. S. DF.I'ARTMKNT OK AGRIClTLTUfiE. 



L'. 1'ores in tli<! summer wood not united into lines, or rarely *'>. 



n. Heartwood reddi.sli brown and very firm ]{ e( l as /,. 



fc. Heartwood grayish In-own, and much more porous lilack axli. 



In the oaks, two groups ran lie i-cadily distinguished by the manner in which the pores are distributed in the 

 summer wood. In the white oaks the pores are very fine and numerous and crowded iu the outer part of the, 

 summer wood, while in the Mark or red oaks the pores are larger, few in number, and mostly isolated. The live 

 oaks, as far as strnettire is concerned, belong to the black oaks, but are much less porous, and are exceedingly 

 heavy and hard. 



III. DiFKi'SK-roitors \Vooi >s. 



[A few indistinctly ring-porous woods of <;roii]> II, ]>, ;unl ri-dar rim may scdiu to IM^OII^ hero.] 



A. I'ores varying in size from large to minute; largest in spring wood, thereby giving sometimes the appearance of 



a ring-porous arrangement. 



1. Heavy and hard; color of heartwuod (especially on longitudinal section) chocolate brown Black walnut. 



'2. Light and soft; color of heart wood light reddish brown Butternut. 



B. Pores all minute and indistinct; most numerous in spring wood, giving rise to a lighter colored /one or line 



(especially on longitudinal section), thereby appearing sometimes ring porous; wood hard, heartwood vinous 

 reddish; pith rays very line, but very distinct. (See also the sometimes indistinct ring-porous cedar elm, and 

 occasionally winged elm, which are readily distinguished by the concentric wavy lines of pores iu the summer 

 wood) CJierri/. 



FIG. 11. Wood of hickory. 



C. Pores minute or indistinct, neither conspicuously larger nor more numerous in the spring wood and evenly 

 distributed. 



1. Broad pith rays present. 



a. All or most pith rays broad, numerous, and crowded, especially on tangential sections, medium heavy 

 and hard, difficult to split Sycamore. 



b. Only part of the pith rays broad. 



a'. Broad pith rays well defined, quite numerous; wood reddish-white to reddish Beech. 



b'. Broad pith rays not sharply defined, made up of many small rays, not numerous. Stem fur- 

 rowed, and therefore the periphery of section, and with it the annual rings, sinuous, bending in 

 and out, and the large pith rays generally limited to the furrows or concave portions. Wood white, 

 not reddish Blue beech. 



2. No broad pith rays present. 



a. Pith rays small to very small, but quite distinct. 

 a'. Wood hard. 



a" Color reddish white, with dark reddish tinge in outer summer wood Maple. 



b". Color white, without reddish tinge Holly. 



V. Wood soft to very soft. 



a". Pores crowded, occupying nearly all the space between pith rays. 



a'". Color yellowish white, often with a greenish tinge in heartwood Tulip poplar, 



Cucumber tree. 



V" . Color of sapwood grayish, of heartwood light to dark reddish brown Sieeet gum. 



ft". Pores not crowded, occupying not over one-third the space between pith rays; heartwood 



brownish white to very light brown Baxswood. 



ft. Pith rays scarcely distinct, yet if viewed with ordinary magnifier, plainly visible, 

 a'. Pores indistinct to the naked eye. 



a". Color uniform pale yellow; pith rays not conspicuous even on the radial section Buckeye. 



V. Sapwood yellowish gray, heartwood grayish brown; pith rays conspicuous on the radial sec- 

 tion Sour gum 



Pores scarcely distinct, but mostly visible as grayish specks on the cross section; sapwood whit- 

 ish, heartwood reddish : Birch. 



h . 



