288 ANATOMY OF THE GYMNOSPERMS 



Radial. Rays locally very resinous throughout ; the ray tracheids low, 

 unequal, marginal, sometimes interspersed. Ray cells more or less 

 contracted at the ends, especially in the summer wood, equal to 7-8 

 spring tracheids; the terminal walls thin, often locally thickened or 

 sparingly pitted, sometimes entire ; the upper and lower walls thicker 

 and strongly pitted in the resinous cells, thinner and sparingly pitted 

 in the nonresinous cells ; the lateral walls with small, oval, bordered 

 pits, the orifice narrow, oblong, 2-6, chiefly 4, per tracheid, in the 

 summer wood rather abruptly reduced to i. Bordered pits numerous, 

 elliptical, in i row, sometimes in pairs. Pits on the tangential walls 

 of the summer wood rather few and not very prominent, flat, often 

 widely scattering, and extending for some distance into the summer 

 wood. 



Tangential. Rays numerous, low to high, rather broad, resinous. The 

 fusiform rays rather narrow, with a small resin canal and thick-walled 

 epithelium. Ordinary rays contracted at the position of the occa- 

 sionally interspersed and very narrow tracheids ; the parenchyma 

 cells conspicuously unequal and variable, from round or oval to 

 oblong, often narrow and high. 



7. P. tricolor, Mayr. 

 Jap. - 6-Tdhi 



Transverse. Growth rings narrow, uniform. The narrow summer wood of 

 6-10 tracheids, about equal to one third to one half the spring wood 

 from which the transition is rather gradual ; not very dense, the tra- 

 cheids much flattened and rounded. Spring tracheids conspicuously 

 squarish, thin-walled, uniform in very regular rows. Resin passages 

 rather large, often with thyloses ; the epithelium composed of very 

 unequal, thick-walled cells. Medullary rays rather prominent, some- 

 what resinous, i cell wide, distant 2-10 rows of tracheids. 



Radial. Rays somewhat resinous, the resin localized; the ray tracheids 

 numerous, prominent, and marginal, often interspersed. Parenchyma 

 cells straight, equal to about 8 tracheids; the terminal walls thin, at 

 first sparingly, soon strongly, pitted throughout ; the upper and lower 

 walls medium, very sparingly pitted, or again thicker and strongly 

 pitted, especially in the summer wood ; the lateral walls with small, 

 elliptical, bordered pits, with an oblong orifice, 2-4 per tracheid, 

 abruptly reduced to I in the summer wood. Bordered pits large, 

 elliptical, or round, in i row. Pits on the tangential walls of the 

 summer wood not very numerous, small, chiefly confined to the outer- 

 most wall. 



Tangential. Rays rather numerous but low to medium, somewhat resinous. 

 The fusiform rays chiefly low, narrow, the usually small resin canal 

 with thick-walled epithelium. Ordinary rays conspicuously contracted 

 at the position of the very narrow, interspersed tracheids; the paren- 

 chyma cells thick-walled, equal and chiefly uniform, oblong, often 

 narrow, rarely oval. 



