354 THE ANATOMY OF WOODY PLANTS 



comparative anatomy and the organization of fossil forms, but the 

 same derivation is likewise indicated by two other series the 

 Taxodineae-Cupressineae on the one hand and the Podocarpineae- 

 Taxineae on the other. The first series, on the basis of com- 

 parative anatomical evidence, formerly possessed the ligneous 

 resin canals and the marginal ray-tracheids of the later Mesozoic 

 Abietineae. The supposed species of Sequoia of the Mesozoic 

 are not representative of the living genus, but have the organiza- 

 tion of araucarian conifers, as has been shown by recent anatomical 

 investigation of the forms from the American Cretaceous. They 

 accordingly have no bearing on the question of the origin of the 

 Taxodineae-Cupressineae. In the case of the series which has 

 been described above as the Podocarpineae-Taxineae, the evidence 

 from fossil forms is practically non-existent in the present state 

 of our ignorance in regard to the organization of the Mesozoic 

 conifers of the Southern Hemisphere. The situation must there- 

 fore be judged on the basis of the living forms. The reproductive 

 structures of the Podocarpineae, particularly those of the genus 

 Podocarpus, are strikingly abietineous and sufficiently clearly 

 indicate the affinities of the subtribe. The primitive Taxineae, 

 obviously in accordance with the established principles of com- 

 parative anatomy, formerly possessed the abundant wood paren- 

 chyma of the Podocarpineae, and their systematic position is 

 therefore elucidated. If the statements in the present paragraph 

 are well founded, evidently both the Taxodineae-Cupressineae 

 and the Podocarpineae-Taxineae are of abietineous origin. 



The time has now come to summarize the phylogenetic affini- 

 ties of the Coniferales, both as regards the general relationship 

 of the tribe and as regards the affinities of its particular subtribes 

 with one another. It seems clear that the Abietineae have on 

 all counts the strongest claim to be considered as primitive repre- 

 sentatives of the Coniferales. These may be summarized as 

 follows: filiation with the Cordaitales and co-ordination with the 

 Ginkgoales; precedence to the Araucariineae, to the Taxodineae- 

 Cupressineae, and to the Podocarpineae-Taxineae. The evidence 

 for the ancestral character of the abietineous conifers may in 

 the future be fuller, but scarcely any stronger, than it is at the 



