INTRODUCTORY TO LAND-VEGETATION 459 



sporangia may be borne in each season, and the spore-production 

 may thus be spread over a long period. This with many accessory 

 features marks the Pteridophytes as higher in the scale of Land- 

 Vegetation than the Bryophytes, foreshadowing that climax of 

 Land-Vegetation which is seen in the Flowering Plants. Nevertheless, 

 apart from the differences of balance and of special development of 

 the two generations, the life-cycle of the Bryophytes and Pterido- 

 phytes is essentially alike. The Archegoniatae may then be held as 

 the primitive vegetation of the Land, sharing with the Seed-Plants 

 the advantages of subaerial life, but still tied down by their primitive 

 method of fertilisation to habitats where external liquid water is at 

 least occasionally accessible. 



