344 



THE ANATOMY OF WOODY PLANTS 



scale the conditions found in the double scales of the ovuliferous 

 strobilus of the Abietineae. The reproductive features conse- 

 quently supply some evidence for the association of the podocarps 



with the abietineous conifers. 

 The organization of the wood in 

 the group under consideration is 

 very similar to that found in the 

 Cupressineae and Taxodineae. 

 The tracheids possess opposite 

 pitting and bars of Sanio. The 

 parenchyma is abundant and 

 scattered throughout the annual 

 ring. A clear difference from the 

 Cupressineae and Taxodineae is 

 supplied, however, by experi- 

 mental evidence, since neither 

 traumatic resin canals nor margi- 

 nal ray-tracheids have been found 

 as yet in any of the genera of the 

 Podocarpineae. We shall prob- 

 ably not make further advance 

 in the final determination of the 

 phylogenetic or evolutionary 

 position of this subtribe of the 

 Coniferales until our present ex- 

 tremely meager knowledge of the 

 fossil conifers of the Southern 

 Hemisphere has been notably in- 

 creased. It seems highly prob- 

 able, on the basis of the organiza- 

 tion of the scales of the female 

 cone and of the sporophylls and 

 spores of the male cone, that the Podocarpineae have abietineous 

 affinities. Their final position will ultimately be determined by a 

 better knowledge of the anatomy of extinct forms. 



Of the coniferous subtribes enumerated in the preceding 

 pages the Taxineae have not as yet been considered anatomically. 



FIG. 250. Longitudinal section 

 of a traumatic resin canal in the same 

 species. 



