1915] 



BESSEY — PHYLOGENETIC TAXONOMY 119 



sporophyte; megasporangia surrounded by one or two en- 

 veloping indusial coats (seed coats); mature seed with or 

 without endosperm (gametophyte tissue). 



The flowering plants are here held to have sprung from 

 cycadean strobiliferous ancestors, probably of the general 

 type of the Bennettitineae, and as a consequence those antho- 

 phyta are considered to be primitive in which the sporophylls 

 are many and distinct. Symphylly and syncarpy are later 

 structural conditions than apophylly and apocarpy. So also, 

 fewer sporophylls in the anthostrobilus is a later condition 

 derived from the earlier polyphyllous structure. The sym- 

 physis of sporophylls is a mode of evolution, and so is their 



aphanisis. 



The plants constituting this phylum are those commonly 

 termed angiosperms, in contrast with the gymnosperms, in- 

 cluding the cycads (Cycadophyta) and conifers (Strobilo- 

 phyta). It appears to the writer, however, that these are 

 more properly three pretty distinct phyla, and that the rela- 

 tionship of the gymnosperms to the angiosperms is so remote 

 that the treatment here given them is more nearly in accord- 

 ance with what is known as to their phylogeny. 



There are two classes, Altemifoliae (monocotyledons) and 

 Oppositifoliae (dicotyledons), of which the second was quite 

 certainly the earlier, as it is now much the larger numerically. 

 Indeed, it is becoming more probable that the monocotyledons 

 are to be regarded as a peculiar side branch which sprang 

 from the primitive dicotyledons after the latter had become 

 well established. Yet the monocotyledons have not developed 

 to as high a rank in any of their orders as have some of the 



dicotyledons. 



Although I have here changed the technical names of these 

 two classes, there is no objection to the retention of the old 

 terms for the English names in popular usage: accordingly 

 on the following pages I shall frequently make such use of the 

 old names. 



Class 32. ALTERNIFOLIAE (MONOCOTYLEDON- 

 EAE). The Monocotyledons. Leaves of young sporophyte 



