344 CRYPTOGAMIA-FILICES. Isoetes. 



Subularia vulgaris erecta, folio rigidissimo. Rail Syn. 306. 



S. lacustris, seu Calamistrum, herba aquatico-alpina. Rail Syn. 

 ed. 1.210. t.2. 



/3. Calamaria folio longiore et graciliore. Dill. Muse. 541. t. 80. 

 /. 2. 



Subularia fragilis, folio longiore et tenuiore. Dill, in Raii Syn. 

 307. 



In the more shallow parts of the bottoms of clear alpine lakes. 



In most of the lakes of North Wales, Scotland, Cumberland, and 

 Westmoreland, composing a sort of green inundated turf. Mr. 

 Lhwyd appears to have first remarked it in Britain. 



Perennial. May, June. 



The long, simple, somevirhat hairy, fibres run perpendicularly down 

 from the tuberous root into the ground. Each plant, having no 

 stem, consists of a tuft of numerous awl shaped /ronds, more or 

 less upright, acute, smooth, obtusely quadrangular, all varying 

 in height, in different individuals, from three to nine inches. In- 

 ternally they are formed of four longitudinal cells, having nu- 

 merous transverse partitions. At the base each frond is dilated, 

 with a membranous edge bordering the solitary, oval, flattened 

 common receptacles above described. Of these that which ripens 

 its contents the latest is judged to be the seed-vessel. The seeds 

 are pure white, granulated all over, as in the East Indian species, 

 whose common receptacle is certainly of but one cell, which, 

 alter the seeds fall out, is lined with their permanent stalks. 



The taller, more slender, and brittle variety /3, observed by Dr. 

 Richardson, may perhaps be caused by those sudden risings of 

 the waters, so frequent in mountainous countries, which will 

 account for all the peculiar characters of this variety. Fish are 

 said to feed, and grow fat, on the Isoetes, 



