Australian Flowering Plants. 215 



has become inure and more herbaceous and correspondingly 

 aggressive with the progress of time, and it appears to have 

 adapted itself to stony and mountainous, as also to cold 

 conditions. 



The more the flowering plants are studied the more is the 

 conclusion forced upon the student that many types have passed 

 through two periods of climatic differentiation, the one prior 

 to the great isolation of Australia, the other after the Eocene, 

 or after the great isolation. The first differentiation appears 

 not to have become so marked as the second. It has been 

 pointed out, however, that the xerophvtie angiosperms just dis- 

 cussed could be explained on the assumption of deserts through- 

 out Cretaceous and Tertiary time with a great zoning of climate 

 in past Eocene time. 



It seems permissible to regard the earlier Senecios as trees, 

 which frequented the open places and which loved moisture. 

 These arborescent forms appear to have populated all the great 

 land blocks before the isolation of Australia from Southern 

 Asia, and the herbaceous habit also appears to have been 

 developed among some of the species even before the isolation 

 was complete. After the great isolation and the gradual dif- 

 ferentiation of climate the Senecios were unable to make much 

 headway in Australia owing to their greater preference for 

 moist, cool places and their inability to flourish well within hot 

 arid regions. In ^Tew Zealand they flourished in the moist, 

 cool climate and the old arborescent habit is preserved in some 

 species. Hawaii, and Juan Fernandez, illustrate in some 

 measure the primary tree type. 



It was in the northern hemisphere, however, that Senecio 

 made its great and aggressive response to the cold changes both 

 towards, and during, the Glacial Period. Over Eurasia and 

 North America the new race spread rapidly, nor did it cease 

 to travel until it reached the Magellan Straits where its prog- 

 ress farther was stayed. In the cold climate of the Chilian 

 heights and of the country abottt Magellan Straits, however, 

 it became strongly developed, about 200 species having been 

 recorded thence. (Carl Eeiche, Flore de Chili.) 



In South Africa on the poor plateau soils Senecio made a 

 magnificent response (200 species) to its environment. 



The Everlastings. The case of Helichrysum and its allies 

 may now be considered. These all belong to Inuloidea?. a tribe 

 with many genera and species but decadent in great measure, 

 although possessing a large and vigorous offshoot from the old 



