246 



THE AMPHIBIOL'S QUILLWORTS. 



water, but it is significant that the peripheral bast bun- 

 dles prominent in Isoetes Niittallii are also present, while 

 the numerous stomata found indicate that it, too, is 

 often exposed to the air. It 'is found 

 only within the range of its relative 

 — from California to Idaho and Wash- 

 ington. Two other forms, described 

 as Isoetes Undcriooodii and Isoetes niida, 

 are now believed to be the same as 

 Isoetes Hozuelli. Mr. Eaton has re- 

 cently described a plant from the same 

 range which he calls Isoetes Piperi. It is distinguished 

 by heavier markings on the megaspores and would seem 

 to be still another variety. 



Me^aspore of 

 Isoetes HowelH. 



