138 Plant Life and Evolution 



to assume a direct connection between these forms 

 and any of the higher plants, until we have a 

 great deal more evidence upon the subject. Never- 

 theless, the possibility of an origin of the higher 

 plants from some gymnospermous forms, allied to 

 the cycads, must be borne in mind in any specula- 

 tions as to the origin of the angiosperms. 



GIN KGO ALES 



The curious maiden-hair tree, or Ginkgo, which 

 we have already referred to, is the sole survivor of 

 an extremely ancient race which was represented 

 by many species in the later Paleozoic and early 

 Mesozoic, some of the later Paleozoic species having 

 actually been referred to the existing genus Ginkgo. 

 In the temple gardens of Japan are many superb 

 specimens of this strange tree. These are sometimes 

 of great size, and are said to be many centuries old. 

 Unlike the cycads, the tree is extensively branched, 

 and looks not unlike a poplar. Its curious fan- 

 shaped leaves, which are deciduous show ?, forked 

 venation like that of a maiden-hair fern ; hence the 

 name, " maiden-hair tree," sometimes applied to it. 



The large seeds, which are borne at the end of 

 short branches, are much like those of Cycas, and the 

 structure of the gametophyte and the development 

 of large motile sperms in the pollen-tube are strik- 

 ingly similar. It seems probable that there is a real 

 relationship between Ginkgo and the cycads, but it 



