224 ANATOMY OF THE GYMNOSPERMS 



Resin cells on the outer face of the summer wood only. 

 Bordered pits not definitely seriate. 



Pits on the lateral walls of the ray cells i-seriate in the cen- 

 tral, 2-3 seriate in the marginal cells which are crystal- 

 logenous. 



6. * * S. Penhallowii. 

 Resin passages present on the outer face of the summer wood. 



Resin cells more or less numerous and scattering throughout the 

 growth ring. 



Bordered pits in 1-2 rows. 



Ray cells (tangential) very large and broad, squarish. 



Pits on the lateral walls of the ray cells 2-6 per tracheid. 



i. S. sempervirens. 

 Ray cells (tangential) oval or round. 



Pits on the lateral walls of the ray cells obliterated. 



3. * * S. Langsdorfii. 

 Resin passages (radial only) with thyloses. 



Resin cells somewhat numerous, scattering throughout the growth 

 ring but most abundant on the outer face of the summer wood. 

 Bordered pits in 1-2 rows. 



Marginal ray cells not crystallogenous. 



4. * * S. Burgessii. 



Resin passages (traumatic) present, both vertically and radially. 

 Resin cells on the outer face of the summer wood only. 

 Bordered pits not definitely seriate. 



Pits on the lateral walls of the ray cells i-seriate in the 

 central, 2-3 seriate in the marginal cells which are crystal- 

 logenous. 



6. * * S. Penhallowii. 



1. S. sempervirens, Endl. 

 Redwood 



Transverse. Summer wood very prominent, of 3-11 tracheids, or upwards 

 of one third the spring wood ; the structure often very open, or when 

 dense sometimes double. Spring wood very open, the large, squarish, 

 or hexagonal tracheids often radially elongated, the walls thin ; tran- 

 sition to the summer wood rather abrupt. Resin cysts contiguous 

 and coalescent and forming an extended tangential series in the 

 initial growth of the spring wood, of distant growth rings. Resin 

 cells rather abundant, very prominent and dark, rather large, scatter- 

 ing through the spring wood. Tracheids rather uniform in very 

 irregular rows. Medullary rays broad, prominent, i cell wide, distant 

 1-12, mpre rarely 20, rows of tracheids. 



