KEY TO THE ISOETESo 



I. Plants normally submerged 



Spores with low tubercles or warts. 7. Bolanderi 

 Spores with slender spines . . /. echitiospora 



Spores with short rounded crests . 7. Macouni 



Spores with worm-like crests . 7. hieroglyphica 



Spores with thin crests sparingly anastomosing 



7. I a cits tr is 

 Spores with many anastomosing ridges 



7. Tucker mani 



II. Plants normally exposed in summer 

 Indusium complete 



Spores with fine warts . . 7. melanospora 



Spores with heavy tubercles . I.flaccidii 



Indusium incomplete 



Spores with faint crests and warts 7. Howcllt 

 Spores with numerous truncate spines 7. Gravesii 

 Spores with spines and short crests 



Mostly spinulose . . 7. saccharata 



Crests often anastomosing 7. riparia 



Spores reticulated 



Ridges sub-continuous . 7. Canadensis 

 Ridges anastomosing 



Ridges thin . . 7. Engelmanni 



Ridges moderately thick 7. veil id a 



Ridges very thick . 7. fovcolata 

 III. Plants seldom if ever submerged 



Spores smooth ... 7. Orcutti 



Spores faintly warty 



Warts few ... 7. Nuttallii 



Warts many 



Commissures wide . 7. inelanopoila 



Commissures narrow . 7. Butlcri 



Spores with short spines . . 7. minima 



