fpENHALLOw] N. AMERICAN TAXACEiE AND CONIFER/E 47 



TAXACE.E. 



Transverse. "Wood wholly devoid of resin-passages and of isolated resin- 

 cells ; the tracheids in more or less regular, radial rows, chiefly small. 



Radial. Tracheids with conspicuous bordered pits on the radial walls, 

 and small, often inconspicuous bordei-ed pits on the tangential walls 

 of the summer wood ; the spiral bands narrow, in double series. 

 Ea}' tracheids wholly wanting. 



Tangential. Medullary rays of one kind only, chiefly one, rarely two- 

 seriate in part. 



Synopsis of Genera. 



1. Eay-cells (tangential) narrowly oblong. 



Tracheids (transverse) chiefly thick-walled and variable, the lumens 

 usually conspicuously rounded, the structure somewhat compact 

 (except T. Jioridana). the spirals rather close. 



1. Taxus. 



2. Eay-cells (tangential) broad, oval or oblong. 



Tracheids (transverse) large, chiefly squarish and rather thin-walled, 

 the structure rather open throughout ; the spirals rather open. 



2. TORREYA. 



I. Taxus, Tourn. 



Transverse. Growth-rings variable and often unconformable. Summer 

 wood chiefly dense and conspicuous, though often very thin ; trach- 

 eids small and more or less rounded ; the structure chiefly dense, 

 more rarely open {T. floridana), with large and squarish tracheids. 



Radial. Spirals of the tracheids rather close. 



Tangential, Eay-cells narrowly oblong. 



Species. 

 T. canadensis, Willcl. 

 T. brevifolia, Nutt. 

 T. floridana, Nutt. 



2. ToRREYA, Arnott. 



Transverse. Growth-rings rather thin, often variable. Summer wood 

 usually very thin ; the tracheids rather large, chiefly squarish, the 

 structure open throughout. 



Radial. Tracheids with much more open spirals. 



Tangential. Eay-cells large, broadly oval or oblong. 



Species. 

 T. californica, Torr. 

 T. taxifolia, Arnott. 



