188 THE GEOLOGICAL HISTORY OF PLANTS. 



In this period, also, we find the earliest representatives 

 of the endogenous plants. It is true that some plants 

 found in the coal-formation have been doubtfully re- 

 ferred to these, but the earliest certain examples would 

 seem to be some bamboo-like and screw-pine-like plants 

 occurring in the Jurassic rocks. Some of these are, it is 

 true, doubtful forms, but of others there seems to be no 

 question. The modern Pandanus or screw-pine of the 

 tropical regions, which is not a pine, however, but a 

 humble relation of the palms, is a stiffly branching tree, 

 of a candelabra-like form, and with tufts of long leaves 

 on its branches, and nuts or great hard berries for fruit, 

 borne sometimes in large masses, and so protected as to 

 admit of their drifting uninjured on the sea. The stems 

 are supported by masses of aerial roots like those which 

 strengthen the stems of tree-ferns. These structures and 

 habits of growth fit the Pandanus for its especial habitat 

 on the shores of tropical islands, to which its masses of 

 nuts are drifted by the winds and currents, and on whose 

 shores it can establish itself by the aid of its aerial roots. 



Some plants referred to the cycads have proved veri- 

 table botanical puzzles. One of these, the Williamsonia 

 gigas of the English oolite, originally discovered by my 

 friend Dr. Williamson, and named by him Zamia gigas, a 

 very tall and beautiful species, found in rocks of this age in 

 various parts of Europe, has been claimed by Saporta for 

 the Endogens, as a plant allied to Pandanus. Some 

 other botanists have supposed the flowers and fruits to be 

 parasites on other plants, like the modern Rafflesia of 

 Sumatra, but it is possible that after all it may prove to 

 have been an aberrant cycad. 



The tree-palms are not found earlier than the Middle 

 Cretaceous, where we shall notice them in the next chap- 

 ter. In like manner, though a few Angiosperms occur 

 in rocks believed to be Lower or Lower Middle Cretaceous 

 in Greenland and the northwest territory of Canada, and 



