148 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



formed from the remains of a flora which was relatively poor in 

 species and almost certainly belonged to a later age. 



Of late Carboniferous time the early Permian was essentially a 

 continuation, though, later, arid conditions became widespread, the 



lie. 39. — Generalized reconstruction ot a Carboniferous forest. 1 he tall, much- 

 branched trees on the left are Lepidodendrou. Below these are Sigilloria and leaves of 

 Lygitiopteris. In the centre foreground is a slender type of Calamite and in the back- 

 ground are much-branched tree types. To the right of the water in the foreground 

 are more Sigillarias and a Tree-fern. On the extreme right are lofty Cordaitales, 

 and, in the undergrowth, several Pteriodosperms, among which is seen a SpheuophyUum. 



big Pteridophytes and the Pteridosperms tending to decline and 

 become replaced by other groups — including the drought-resisting 

 Cycadophytes and more Conifers. At the same time the character- 

 istic if limited Glossopteris flora existed under the relatively cold 

 conditions of the south, in the areas of India, Africa, South America, 

 Australasia and x^ntarctica that were supposedly occupied by the 

 ancient ' Gondwanaland '. For the Permian was a period of active 

 mountain building and rearrangement of large areas of land and sea, 

 with severe glaciation at least in the South. It may be considered as 

 starting the real age of higher Gymnosperms, which held sway 

 throughout the Mesozoic era. In contrast with the generally uniform 

 growth of trees in the coal age, those which grew during and immedi- 



