KEY TO SPECIES 285 
II. POROUS WOODS: BROADLEAF WOODS: HARD- 
WOODS 
A. Ring porous wood. 
1. Pores in radial lines branching more or less toward the 
margin of the growth ring. 
a. Broad pith or medullary rays absent; rays uniform 
and inconspicuous. Wood rather light, mod- 
erately stiff, but not strong. 
al. Pores in spring wood very numerous and in a 
wide zone. Color brown, odor very mild. 
Astringent taste. 
CHESTNUT—Castanea dentata 
b. Broad rays present. Wood heavy, hard, strong, 
characteristic odor. 
b1. Pores in sprmg wood in few (1-8) rows, 
usually not crowded, transition to smaller 
pores of summer wood abrupt. Large 
rays often very high on lengthwise sec- 
tion; maximum 5 inches. Abundant 
tyloses.} 
WHITE OAK—Quercus alba 
62. Pores in early wood mostly in several (3-5) 
rows, crowded; transition to smaller 
pores in summer wood gradual. Pores 
in summer wood comparatively large, 
circular outlines. Large rays, compara- 
tively low, rarely 1 inch high on length- 
wise section. Tyloses absent. 
RED OAK—Quercus rubra 
2. Pores in spring wood in a single row or in a zone of 
2-3 rows. Pores in summer wood arranged tan- 
gentially in conspicuous festoons or concentric 
bands, usually continuous, wavy, the pores 
minute or small. 
a. Rays rather indistinct. Pores in spring wood 
large, forming a continuousrow. Wood rather 
light, but hard to split. Texture coarse. 
WHITE ELM—Ulmus americana 
1'Tyloses are pith-like cells that sometimes fill the pores. 
