208 The Palaeontological Record. II. Plants 



since the discovery of the bisexual flowers of the Bennettiteae, 

 have expressed different views as to the nearness of their relation 

 to the higher Flowering Plants, but the points of agreement are 

 so many that it is difficult to resist the conviction that a real 

 relation exists, and that the ancestry of the Angiospenns, so long 

 shrouded in complete obscurity, is to be sought among the great 

 plexus of Cycad-like plants which dominated the flora of the world 

 in Mesozoic times 1 . 



The great complexity of the Bennettitean flower, the earliest 

 known fructification to which the word "flower" can be applied 

 without forcing the sense, renders it probable, as Wieland and 

 others have pointed out, that the evolution of the flower in 

 Angiospenns has consisted essentially in a process of reduction, 

 and that the simplest forms of flower are not to be regarded as the 

 most primitive. The older morphologists generally took the view 

 that such simple flowers were to be explained as reductions from 

 a more perfect type, and this opinion, though abandoned by many 

 later writers, appears likely to be true when we consider the elabora- 

 tion of floral structure attained among the Mesozoic Cycadophyta, 

 which preceded the Angiosperms in evolution. 



If, as now seems probable, the Augiosperms were derived from 

 ancestors allied to the Cycads, it would naturally follow that the 

 Dicotyledons were first evolved, for their structure has most in 

 common with that of the Cycadophyta. We should then have to 

 regard the Monocotyledons as a side-line, diverging probably at a 

 very early stage from the main dicotyledonous stock, a view which 

 many botanists have maintained, of late, on other grounds 2 . So far, 

 however, as the palaeoutological record shows, the Monocotyledons 

 were little if at all later in their appearance than the Dicotyledons, 

 though always subordinate in numbers. The typical and beautifully 

 preserved Palm-wood from Cretaceous rocks is striking evidence 

 of the early evolution of a characteristic monocotyledonous family. 

 It must be admitted that the whole question of the evolution of 

 Monocotyledons remains to be solved. 



Accepting, provisionally, the theory of the cycadophytic origin 

 of Angiosperms, it is interesting to see to what further conclusions 

 we are led. The Bennettiteae, at any rate, were still at the gyrn- 

 nospermoiis level as regards their pollination, for the exposed 



1 On this subject see, in addition to Wieland's great work above cited, F. W. Oliver, 

 " Pteridosperms and Augiosperms," New Phytologist, Vol. v. 1906; D. H. Scott, "The 

 Flowering Plants of the Mesozoic Age in the Light of Recent Discoveries," Journal R. 

 Microscop. Soc. 1907, and especially E. A. N. Arber and J. Parkin, " On the Origin of Angio- 

 sperms," Journal Linn. Soc. (Bot.) Vol. xxxvm. p. 29, 1907. 



2 See especially Ethel Sargant, " The Reconstruction of a Race of Primitive Angio- 

 sperms," Annals of Botany, Vol. xxn. p. 121, 1908. 



