92 Prof. Brawn's Notice of the Charce, of North America. 



Art. XII. — A Brief Notice of the Charce of North America ; by 

 Prof. Alexander Braun, — communicated by Dr. Engelmann. 



Besides the Equiseta, Prof. Braun has devoted much attention 

 to other families of Cryptogamous plants, such as the Rhizocar- 

 pece ; of which he has lately published two new North American 

 species of Marsilea: viz. M. uncinata, found in 1835 by the wri- 

 ter of this note in Arkansas ; and M. mucronata, discovered in 

 the year 1839 by Mr. Geyer, in Nicollet's Northwestern Expedi- 

 tion, along the saline prairies near Devil's Lake. Both are nearly 

 related to M. vestita, Hook. & Am. of Oregon, but very differ- 

 ent from the European M. quadrifolia. But Prof. Braun 's espe- 

 cial favorites are the Charce, which he has very thoroughly inves- 

 tigated, and intends soon to describe monographically. As these 

 obscure plants are seldom collected by our botanists, he has not 

 enjoyed so good opportunities of studying American specimens as 

 could be wished. He therefore urgently requests American bota- 

 nists to aid him by the communication of their collections in this 

 genus, (either in the way of loan or exchange,) in order that the 

 species of this country may be more satisfactorily elucidated.* 

 The subjoined list comprises eleven North American species, 

 which have fallen under his notice in various European herbaria. 

 Five of these are identical with European species ; four are dis- 

 tinct, but nearly related forms ; while two belong to a section 

 which has no known representative in Europe. G. E. 



Charm of North America. 

 A. Charge epigynje, A. Braun. (Nitella, Agardh, partly.) 



1. Ch. flexilis, Linn, (vera?) — Sterile specimens, Pennsyl- 

 vania ? Schweinitz in herb. Zeyher. In the Merrimac, Massa- 

 chusetts, Greene. 



2. Ch. glomerulifolia, A. Braun. — (Subspecies of C. flexi- 

 lis.) In the Merrimac, Greene. 



3. Ch. mucronata, A. Braun. — [C. flexilis of authors, partly) 

 var. Americana? A. Braun. In the Merrimac, Greene. 



* Dr. Engelmann of St. Louis, tind also Prof. Gray of Harvard Univ«rsity, will 

 cheerfully take charge of parcels or communications addressed to Prof. Braun. 



