380 PART III. THE CLASSIFICATION OF PLANTS. 



the arcliesporium is multicellular ; the embryo has a suspensor, 

 but no primary root. All the existing forms are eusporangiate. 



The characters of the gametophyte vary widely. The sperma- 

 tozoids are biciliate. 



Sub-Class HOMOSPORE.E : the sporophyte produces spores of one 

 kind only ; the prothallia are free, more or less tuberous, mon- 

 oecious. 



Order 1. Lycopodiacece. Order 2. Psilotacece. 



Sub-Class HETEROSPOREJ: : the sporophyte produces microspores 

 and macrospores ; the former gives rise to male, the latter to 

 female, prothallia; the prothallium does not become free from the 

 spore. 



Order 1. Selaginellacece. 



The relations of these various groups may be simply expressed 

 as follows : 



EQUISETIN^E. LYCOPODIN.E. 



Homosporous Filices \Lepto- 



Ueterosporous Hydropterideae / sporanyiatc. 



HoTHosporous fOphioglosBaceiB} Equigeta ce ffi _/^opodiace ^ 



vMarattiaceae l IPsilotaceae ) V Eusporangiate. 



Heterosporous Isoetaceae (none existing) Selaginellactte ) 



