SYSTEMS OP CLASSIFICATION 23 



1. Asexual, or Flowbrless Plants. 



Stem and leaves imdistinguishable . Class 1. Tliallogens. 

 Stem and leaves distinguishable . . Class 2. Acrogens. 



2. Sexual, or Flowering Plants. 



Fructification springing from a thallus Class 3. Ehizogens. 

 Fructification springing from a stem. 

 Wood of stem youngest in the 

 centre ; cotyledon single. 



Leaves parallel-veined, perma- 

 nent ; wood of the stenr always 

 confused .... Class 4. Endogens. 



Leaves net-veined, deciduous ; 

 wood of the stem, when peren- 

 nial, arranged in a circle with 

 a central pith . . . Class 5. Dictyogens. 



Wood of stem youngest at the circum- 

 ference, always concentric ; co- 

 tyledons two or more. 



Seeds quite naked . . . Class 6. Gymnogens. 

 Seeds enclosed in seed-vessels . Class 7. Exogens. 



The Exogens were further divided into four sub-classes 

 thus : — 



Sub-Glass 1. Diclinous Exogens, or those with unisexual flowers, 

 and without any customary tendency to form 

 hermaphrodite flowers. 



Sub-Class 2. Hypogynoiis Exogens, or those with hermaphrodite 

 or polygamous flowers ; and stamens entirely 

 free from the calyx and corolla. 



Sub-Class 3. Perigynous Exogens, or those with hermaphrodite 

 or polyganaous flowers ; and with the stamens 

 growing to the side of either the calyx or corolla ; 

 ovary superior, or nearly so. 



Sub-Class 4. Epigynous Exogens, or those with hermaphrodite or 

 polygamous flowers, and with the stamens grow- 

 ing to the side either of the calyx or corolla ; 

 ovary inferior, or nearly so. 



None of the other classes are divided into sub-classes, but 

 of Endogens four sections are distinguished thus : — 



