THE PTERIDOSPERMS AND THE SEED 257 



referred to the same stock, for evidence has recently 

 been adduced that the small group of the Gnetales (the 

 only outstanding Gymnospermous family) may have been 

 derived, by reduction of the floral organs, from forms 

 allied to the Bennettitales. 



" It thus appears, if the views here taken are justified, 

 that the whole of the Spermophyta, whether Angiosper- 

 mous or Gymnospermous, were ultimately derived, 

 through primitive Seed-plants of the nature of Pterido- 

 sperms, from the same stock with the Ferns." 



THE PHYLOGENY OF THE ANGIOSPERMAE 



If, as you will now see, there is good reason to believe 

 that the Bennettitales represent a very ancient type 

 of seed plant which possessed a hermaphrodite flower, 

 and which came off from a stock that gave origin to our 

 existing flowering plants or Angiosperms, it follows that 

 we must revise completely our ideas on the phylogeny 

 and classification of these plants, and reject both the 

 schemes that are at present in common use. The majority 

 of English botanists have clung tenaciously to the system 

 of Bentham and Hooker in some form or another. One 

 of the most recently published text-books (that of Ganong, 

 in 1917) emphasises the division of Angiosperms into 

 " two sharply marked sub-classes," Monocotyledons and 

 Dicotyledons, and goes on to treat of the former group 

 first, starting with such "orders" as Pandanales, Naiadales, 

 Graminales, Palmales, and Arales as " primitive " Mono- 

 cotyledons, leading up to " differentiated " and 

 " specialised " orders. The Dicotyledons are similarly 

 treated and discussed under " primitive " orders, 

 " differentiated " orders, and " specialised " orders. The 

 ' 'jgrimitive " Dicotyledons are held._to include such 

 plants as the peppers, willows, beeches, aiders,, elms, figs, 

 and a host of others with correspondingly low floral 

 organisation. In this respect Ganong follows Engler's 



17 



