24 LEAFLETS. 



siOABiA as a genus ; though the Linnsean notion has still seemed 

 to prevail, doubtless for the most as a mere prejudgment, 

 during the nineteenth century. 



Among earlier authors there are some who distinguished two 

 genera, Persicaria with mild, and Hydropiper with pungent or 

 peppery herbage ; and the aquatic species were even again by 

 some reckoned a distinct genus called Potamogeton. It is indeed 

 almost certain that the real Potamogeton of ancient botany is 

 Persicaria amphibia ; and on this account Bubani, in the Flora 

 Pyrensea lately published, assigns the modern Potamogeton a new 

 name. And so, it is a mistake on the part of Mr. Small in his 

 new flora to have placed our native homologue of P. amphibia 

 first in his list of the species, as if it were typical of Persicaria ; 

 for it is not. P. maculosa, for which Mr. Small has coined a 

 new and duplicate binary, is the type of Persicaria. 



The following members of the genus, formerly published by me 

 under Polygonum, are here transferred : P. fusiformis (Eryth. 

 i. 259), OMISSA, FALLAX, ARCUATA (Pitt. V. 300, 201). 



Other Nortli American species not hitherto transferred are 

 P. CARETi (Olney, E. I. PI. 29), Hartwrightii (Gray, Am. Acad, 

 viii. 294), cocciifrBA (Muhl. iu Willd. Enum. 428), rigiddla 

 (Sheld. Minn. Studies, i. 14), Ludoyiciaka (Meisn. in DC, xiv. 

 116). This last Mr. Small may have failed to distinguish from 

 Persicaria segetum, in the grammar of whose specific name he 

 has also erred, supposing it to be an adjective, which it neither 

 is nor can be made, except as segtalis. 



In the group of species of which the Old World Persicaria 

 amphibia is typical I have at intervals, as opportunity was given, 

 during years pursued field studies, and made copious specimens 

 vnth a view of revising it, at least as it is represented in North 

 America ; and I have long enough deferred the placing upon 

 public record of certain important biologic facts observed by me 

 in relation to these plants. 



All who have attained to even a superficial knowledge of their 

 history are aware that the specific name amphibia was given to 

 an Old World species because it was familiarly known to be 

 amphibious, so to speak ; one form, or variety, as they called it, 



