n6 ANGIOSPERMAE 



system, the gymnosperms stand, for the sake of convenience 

 as Rendle puts it, between the dicotyledons and mono- 

 cotyledons, but more recent workers have generally 

 placed them, in accordance with the progress of our 

 knowledge of the genetic origin of plants, at the 

 beginning of the system of Flowering Plants. 



This sequence of classes, viz. 

 Gy mno sperms, Mono.coty ledons, Dicotyledons, 

 is apt to give the impression that the monocotyledons 

 represent an earlier and more primitive type of the 

 angiosperms, thus constituting an intermediate stage of 

 development between the gymnosperms and the dicoty- 

 ledons. But that is not so, for the most primitive of 

 living angiosperms are to be found among the dicotyledons 

 and not among the monocotyledons, where no such 

 primitive characters occur, and although we do not know 

 the connecting links between the present angiosperms and 

 the gymnosperms, the gap in our knowledge would not 

 be larger if no monocotyledonous plants were known to 

 us either in the living or the fossil state. 



Both, dicotyledons and monocotyledons, as we know 

 them at present, have originated from some primitive 

 angiosperms, .which are now extinct and of which no 

 records exist, for unfortunately no fossil remains of plants 

 are known which could throw some light on the nature of 

 these early ancestors of the recent angiosperms. 



"There is no document available," as Laurent* says, "which 

 would definitely indicate the origin of the mysterious appearance of 

 the class (viz. the dicotyledons)" ; and ZEiLLERf states at the same 

 time: "While we do not rind any trace or dicotyledons and hardly 

 any indications of monocotyledons in the Upper Jura of Portugal, 

 we see them both at the beginning of the lower cretaceous period of 

 the same region, that means to say only a little higher, establish 

 themselves and multiply rapidly." 



* 1,. Laurent, Les progres tic la paleobotanique angiospermique dans la demierc 

 decade. Progressus Rei Botanies, Vol. i, p. ^67. 1907. 



t R. ZEILLER, Les progres de la paleobotany uc de l'cre des gymnospcrmes. Ibid., 

 Vol. 11, p. 225. 1907. 



