CHAPTER XLVI. 



CUPRESSINEAE. 



THE published records of fossil Conifers would seem to justify 

 the conclusion that the Cupressineae were widely distributed and 

 represented by a wealth of genera during the latter part of the 

 Mesozoic era particularly in the later Jurassic floras, but on closer 

 inspection of the material a student, having any familiarity with 

 the external features of recent genera, cannot fail to recognise 

 the wholly inadequate nature of the data on which the systematic 

 determinations are based. It is undoubtedly true that in the 

 later Jurassic and Lower Cretaceous floras Conifers agreeing 

 generally in habit and in the possession of appressed imbricate 

 leaves with such genera as Cupressus, Chamaecyparis, and Thuya 

 were among the most characteristic types : some have the leaves 

 in decussate pairs with an occasional tendency to a spiral phyllo- 

 taxis while others possess leaves of the same form but spirally 

 disposed. Almost all are sterile and when cones are present the 

 form and arrangement of the scales often suggest comparison with 

 recent types other than the Cupressineae. In the Chapter on 

 recent Conifers attention is called to the inconstancy of leaf- 

 arrangement in certain species and to the close resemblance 

 between vegetative shoots of plants belonging to different families. 

 Fossil coniferous branches referred by authors to the Cupressineae 

 afford a striking illustration of the insufficiency of the evidence 

 on which sterile impressions have been named. This statement, 

 though primarily concerned with Mesozoic records, applies also 

 to many Tertiary species. The records of the rocks clearly show 

 that European Tertiary floras contained a considerable number of 

 Cupressineous types that are now confined to other regions, but 

 a critical examination of the older fossils leads to the conclusion 

 that in very many cases accurate determination of the affinities 

 of sterile branches, superficially resembling existing members of 

 the Cupressineae, is impossible without additional information. 



