SUBKINGDOM SPERMATOPHYTA 347 



genera, occurred. Besides these, a second suborder, now quite 

 extinct, was represented by numerous species. These were the 

 Bennettiteae, which were much like the existing Cycads, but had 

 much more complicated flowers. 



Coniferae. Most of the Conif erse appear in the later Mesozoic and 

 early Tertiary, when certain genera, like Sequoia, Torreya, and 

 Taxodium, which are now much restricted in their range, were very 

 widely distributed. 



Affinities of Gymnosperms 



The origin of the Gymnosperms and their relation to the Angi- 

 osperms are by no means clear. The Cycads are undoubtedly 

 related to the Ferns, but the origin of the Conifers and Gnetaceae 

 is extremely uncertain. There is evidence that the Conifers have 

 arisen from Lycopods, perhaps like the fossil Lepidodendra, but 

 this is by no means generally accepted. The Cordaitese have been 

 suggested as forms intermediate between Cycads and Conifers, but 

 this is open to doubt. Still more uncertain is the origin of the 

 Gnetaceee. 



1. De Bary, A. Comparative Anatomy. 

 '96. 2. Britton, N.' L., and Brown, A. Illustrated Flora of the Northern 



United States, Vol. I. 1896. 

 '80. 3. Brewer, W. H., and Watson, S. Botany of California (Geological 



Survey of California), Vol. II. 1880. 



'01. 4. Coulter, J. M., and Chamberlain, C. J. Morphology of Spermato- 

 phytes. Pt. I, Gymnosperms. New York, 1901. 

 (This is the most recent work on Gymnosperms, and contains a 

 full bibliography.) 

 '97. 5. Chapman, A. W. Flora of Southern United States. Cambridge, 



Mass, 1897. 

 '89. 6. Eichler, A. W. Cycadaceae, Coniferse, and Gnetacese, in Engler and 



Prantl, Nat. Pflanzenfamilien, II Theil. 1889. 

 7. Goebel. Outlines. 



8. Organography. 



9. Gray, A. Manual of Botany. 

 '95. 10. Lennnon, J. G. Handbook of West-American Cone-bearers. San 



Francisco, 1895. 



'82. 11. Luerssen, Chr. Handbuch der syst. Botanik, Bd. II. Leipzig, 1882. 

 '96-'98. 12. Sargent, C. S. Silva of North America, X, XI, XII. Boston, 

 1896-1898. 



13. Strasburger, E. Botanisches Practicum. 



14. Van Tieghem, Ph. Traite" de Botanique. 



15. Vines, S. H. Text-book of Botany. 



16. Warming, E. W. Handbook of Systematic Botany. 



17. Watson. See Brewer. 



