[From the Bulletin op the Torrby Potanical Club 35: 457-46s- 1908I 



Notes on Philotria Raf. 



Per Axel Rydherg 



When trying to determine the Rocky Mountain specimens of 

 Philotria, I happened to run across Caspary's very interesting 

 paper on " Die Hydrilleen " in the Jahrbiichcr fiir wissenschaft- 

 liche Botanik.* It is rather surprising that very little has been 

 written in this country on this American genus, when Caspary 

 devotes over 50 pages to this genus and 137 pages to the tribe 

 Hydrilleae. The genus needs, however, a good deal of more criti- 

 cal study in the field and these notes are written to call attention 

 to this very interesting genus of water plants. I shall here give 

 a short recapitulation of its history. 



The genus was first described in Michaux's Flora Boreali- 

 Americana f under the name Elodea, which, however, is antedated 

 by Elodes Adans. Here the genus is characterized as having 

 hermaphrodite flowers with three stamens, thick filaments, cordate 

 anthers, and three bifid styles. The leaves in E. canadensis Michx. 

 are described as being oblong and obtuse. 



Muhlenberg % referred the plant to the Old World Serpicula 

 verticillata, described the staminate flowers as 4-merous, and added 

 a variety angnstifolia with narrow leaves. 



The next description we find in Pursh's Flora Americae Septen- 

 trionalis § as Serpicula occidentalis. The description here agrees 

 with that in Michaux's Flora, except that the leaves are described 

 as linear, acute, and finely serrulate. 



Rafinesque || gave no description, but merely changed 

 Michaux's Elodea to Philotria on account of the earlier Elodes of 

 Adanson. 



Nuttall ^ proposed a new genus Udora and cited Elodea 



*i: 377-513- 1858. 



t I : 20. 1803. 



f Cat. PI. Am. Sept. 84. 1813. 



§1 : 23 and 33. 1814. 



II Am. Monthly Mag. 2 : 175. 1818. 



IT Gen. N. Am. PI. 2 : 242. 1818. 



457 



