358 TRANS. ST. LOUIS ACAD. SCIKNCE. 



The Genus Isoetes in North America. 

 By Dr. George Engelmann. 

 § 1. History ^/Isoetes hi North America. 



The Isoetes., insignificant and apparently sterile as they are^ 

 were long overlooked or ignored by our botanists, so that until 

 thirty or forty years ago very few specimens were collected, and 

 none were distinguished from /. lacustris^ if we except Nuttall's 

 guess at his Oregon discovery ; but the genus has attracted so 

 much attention, and lately so many forms have become known, 

 that it seems to me an interesting task to trace up the history of 

 the discovery of the different species and their varieties, and of 

 the area of their distribution, and then the date of their publi- 

 cation, before I enter into their scientific description. 



I. DISCOVERY. 



1806 (.^). The first notice which we have of an Isoetes in 

 North America is given in Pursh's Flora, ii. 671, where he states 

 that '■'■ Isoetes lacustris" grows in the bottom of Oswego river, 

 near the falls, and adds his v. v.., which means that he saw it liv- 

 ing, and therefore probably found it himself; and as he travelled 

 through the regions near the Great Lakes in 1806, it was proba- 

 bly in that year that he met with it. I have not seen Pursh's 

 specimens, but doubt not but that it will have to be referred to 

 /. echinospora, var. Braunii, the only form thus far known from 

 Western New York. 



1815. Th. Nuttall collected " /. lacustris" abundant along 

 the inundated gravelly and miry shores of the Delaware at Gib- 

 sonville (now a part of Philadelphia) on Aug. 22d, according to 

 the label of a specimen in Collins' Herbarium, presented to me 

 by E. Durand. It proves to be /. riparia. 



i82o(.?). L. von Schweinitz obtained in the Catskill Moun- 

 tains in New York /. lacustris ; some of his specimens are now 

 found in the Herb. Philad. Acad. Natural Science and one in 

 the St. Petersburg Imperial Herb. Some of them are labeled 

 "Catskill Mountains" and others "Bethlehem," the latter, which 

 was von Schweinitz's residence, probably by mistake. One of 

 the specimens was loaned by the late Elias Durand — in whose 

 possession it was — to Durieu de Maissonneuve, who founded on, 



