PINUS 303 



Bordered pits in 1-2 rows. 



Pits on the lateral walls of the ray cells 1-6, chiefly 

 2-4, per tracheid. 



Ray tracheids high, very strongly reticulated 

 throughout. 



41. P. cubensis, 



Pits on the lateral walls of the ray cells 2-5, chiefly 

 4, per tracheid. 



Ray tracheids sparingly interspersed, predomi- 

 nant, strongly dentate, and somewhat retic- 

 ulated in the summer wood. 



38. P. Sabiniana. 



Ray tracheids commonly predominant, often 

 interspersed and very strongly reticulated 

 throughout. 



40. P. palustris. 



Pits on the lateral walls of the ray cells 1-6, chiefly 

 4, per tracheid. 



Ray tracheids sparingly (rarely strongly) retic- 

 ulated throughout. 



39. P. taeda. 

 Summer wood open. 



Bordered pits in i row or sometimes in pairs, the latter 

 sometimes numerous (P. arizonica). 



Pits on the lateral walls of the ray cells (i) 1-2, 

 rarely 6, chiefly 2 ; and (2) 1-3 per tracheid. 

 Tracheids sparingly predominant and sparingly 

 reticulated. 



37. P. insignis. 



Pits on the lateral walls of the ray cells (i) 2-4; 

 and (2) 2-3 per tracheid. 



Ray tracheids strongly predominant and 

 strongly reticulated. 



29. P. Torreyana. 



Pits on the lateral walls of the ray cells 2-4 per 

 tracheid. 



Ray tracheids dentate and somewhat reticulated 

 throughout, sometimes interspersed and pre- 

 dominant. 



28. P. tuberculata. 



Pits on the lateral walls of the ray cells 2-4, chiefly 

 4, per tracheid. 



