CONTENTS ix 



2. Selaginellales 230 



3. Lepidodcndrales 238 



4. Isoetales 241 



3. Equisetinae 247 



1. Hyeniales 247 



2. Sphenophyllales 248 



3. Equisotales 250 



4. Calamitales 258 



VII. PTERIDOPHYTA (CONTINUED) 260 



4. Filicinae 260 



1. Coenopteridales 260 



2. Ophioglossales 261 



3. Marattiales 270 



4. Filicales 276 



5. Hydropteridales 292 



Comparison of the Classes of Pteridophytes 303 



General Conclusions 304 



VIII. SPERMATOPHYTA 309 



1. Gymnospermae 310 



1. Cycadofilicales 311 



2. Bennettitales 315 



3. Cycadales 319 



4. Cordaitales 330 



5. Ginkgoales 333 



6. Coniferales 340 



7. Gnetales 354 



IX. SPERMATOPHYTA (CONTINUED) 362 



2. Angiospermae 362 



Vegetative Organs 363 



The Flower 372 



Chief Orders of Angiosperms 399 



Comparison of Gymnosperms and Angiosperms 408 



General Conclusions 409 



X. EVOLUTION OF THE PLANT KINGDOM 412 



Prominent Evolutionary Tendencies 415 



Evolution of Sex 417 



Alternation of Generations 422 



Selected References 427 



Glossary 431 



Index 445 



