270 Proceedings of the Ohio State Academy of Science. 



CLASSIFICATION OF PTERIDOPHYTES. 



Archegoniata. Archegoniates. 



The intermediate plants; normally aerial plants but mois- 

 ture-lovnig' ; always with an alternation of generations, the ga- 

 metophyte comparatively large and often hermaphrodite in the 

 lower forms but minute and always unisexual in the highest ; 

 the sporophyte small and without vascular tissue and perma- 

 nently parasitic in the lower forms but large and with vascular 

 tissue and becoming independent when mature in the higher ; 

 either homosporous or heterosporous, eusporangiate or leptospo- 

 rangiate, never seed-producing ; growing point commonly with a 

 definite, two- or three-sided apical cell ; stems sometimes having 

 secondary thickening" by means of a more or less perfect cam- 

 bium or by division in the cortical cells ; oosphere produced in 

 an ovary of definite character called an archegonium and always 

 cutting off a ventral canal cell ; fertilization asiphonogamic, the 

 spermatozoids swimming through water. 



1. Sporophyte without roots, leaves or fibrovascular tissue 



Bryophyta. Mosses and Liverworts. 



1. Sporophyte independent when mature with true roots, leaves, and 



fibrovascular tissue Pteridophyta. 2. 



2. With one kind of nonsexual spores Pteridophyta Homosporae. 



2. With two kinds of nonsexual spores. ... Pteridophyta Heterosporae. 



In this manual the Pteridophytes are still classified in their 

 subkingdoms representing the lower and higher stages of de- 

 velopment. They may more properly be classified according to 

 their natural relationships into three great branches or phyla as 

 follows : 



I. Ptenophyta. About 4,500 known living species. Vas- 

 cular seedless plants with comparatively large multiciliate sperms 

 and usually with large, commonly compound leaves, the sporo- 

 pliylls not in cones. 



