20 PLANT GEOGRAPHY 



in fact, as are the Dicotyledons to-day. The remarkable 

 type, Bennettites, Cycads bearing lateral flowers with 

 spiral bracts, a whorl of compound pinnate staminal 

 leaves with numerous pollen-sacs and stalked ovules 

 developing into dicotyledonous exalbuminous seeds, 

 occurs in the upper Gondwana series of India; while its 

 abundant representation in Europe and North America 

 is an instance of the uniformity that once again charac- 

 terised the vegetation of the world in Lower Secondary 

 times after the Permo-Carboniferous glaciation. Other 

 Cycadophyta were so numerous, and of such world-wide 

 distribution, that the name "Age of Cycads " is almost 

 as appropriate as " Age of Gymnosperms " for the 

 Triassic and Jurassic periods. 



Not till after the deposition of our Wealden, or Lower 

 and Middle Neocomian, beds does there seem to be any 

 indication of the sudden advent and rapid advance of 

 Brongniart's third "Reign," that of Angiosperms; nor 

 is there any clear sign of the existence of botanical zones 

 or regions. 



As towards the close of the Palaeozoic age, so towards 

 that of the Mesozoic, the great change in vegetation ante- 

 dates that in animal life and stratigraphical succession. 



It is now generally agreed that a most probable 

 ancestry for Angiosperms is to be looked for in the 

 neighbourhood of Cycadophyta such as the early 

 Mesozoic genus Bennettites. If so, it would follow that 

 Dicotyledons, which are nearer in structure to the 

 Cycads, would have been evolved before Monocoty- 

 ledons. There is, in fact, much anatomical evidence 

 that Monocotyledons are an early branch from the 

 dicotyledonous ancestral stock; but there is little, if 

 any, stratigraphical evidence of the one class having 

 preceded the other. 



CHAPTER V 



THE COMING OF OUR MODERN ANGIOSPERMS 



IN point of numbers including as they do more than 

 1 00,000 species in size including as they do the gigantic 

 gum trees of Australia in the area they cover, in variety 

 of form and of adaptation to differing circumstances, 

 the Angiospermia, or fruit-bearing Spermatophytes, 



