PINUS 327 



23. P. Thunbergii, Parl. 



Jap. = Ktiromatsu 



Transverse. Growth rings rather broad, variable. Summer wood dense, 

 sometimes equal to the spring wood from which the transition is 

 abrupt, rarely gradual, often double ; the rounded tracheids rather 

 equal in regular rows. Spring tracheids large, hexagonal, unequal 

 in regular rows, the walls rather thin. Resin passages rather nu- 

 merous, rather large and scattering; the epithelium in 1-2 rows of 

 very large and very thin-walled cells not extending much beyond the 

 central canal ; nonresinous ; in the summer wood the layer next the 

 canal is much compressed and the cells are barely recognizable. Med- 

 ullary rays few, not very broad or prominent, distant 2-8 rows of 

 tracheids. 



Radial. Rays nonresinous ; the ray tracheids more or less dentate but not 

 reticulate, generally predominant and marginal, not interspersed. Ray 

 cells of one kind only, straight ; the terminal walls thin and entire ; the 

 upper and lower walls thickish and entire or distantly and obscurely 

 pitted ; the lateral walls with very large, oblong, or lenticular pits, 

 almost strictly i, rarely 2, per tracheid, in the summer wood becoming 

 distinctly bordered, when they are broadly oval with a long, slitlike 

 orifice. Bordered pits large, elliptical, not very numerous, in i row. 

 Pits on the tangential walls wholly wanting. 



Tangential. Fusiform rays rather numerous but low and broad, the chiefly 

 rather short terminals wholly composed of small, oval tracheids, and 

 a few parenchyma cells, the inflated portion composed of very thin- 

 walled cells much broken out. Ordinary rays rather numerous, low to 

 medium, nonresinous, not very broad but presenting two principal 

 aspects : (i) narrow rays composed of a few central, oval parenchyma 

 cells and several variable, terminal tracheids ; and (2) broader rays 

 composed of oval parenchyma cells and a few terminal and small 

 tracheids. 



24. P. densiflora, Sieb. et Zucc. 

 Jap. = Akamatsu 



Transverse. Growth rings very uniform. Summer wood one half the spring 

 wood, from which the transition is abrupt, chiefly dense but somewhat 

 variable, the tracheids rounded, unequal in regular rows. Spring tra- 

 cheids hexagonal, rather uniform, in regular rows, the walls thickish. 

 Resin passages numerous, large, scattering; the epithelium in 1-2 

 rows of thin- and thick-walled cells, easily broken out and generally 

 wanting, nonresinous. Medullary rays few, not very prominent, very 

 narrow, rather obscure, distant 2-20 rows of tracheids. 



Radial. Rays nonresinous ; the ray tracheids dentate, sparingly reticulate 

 in the summer wood, usually predominant and marginal, sparingly 

 interspersed. Ray cells of one kind only and straight ; the terminal 

 walls thin and entire ; the upper and lower walls thin, somewhat uni- 

 form, not obviously pitted; the lateral walls with very large and 



