44 Rhodora [February 



men in his possession in 1753 and labelled by him with the descrip- 

 tive phrase assigned to E. fluviatile in the Species Plantarum.* To 

 this Linnaeus added in the Flora Suceica, 305 (1745) another species, 

 "Equisetum caule nudo laevi." He retained both in the Species 

 Plantarum, giving to the latter the specific name limosum. This 

 treatment seems to have been generally accepted by European authors 

 for some thirty years, the name fluviatilc, however, being often applied 

 to E. Telmatcia Ehrh., an error which Linnaeus had made possible 

 by citing under E. fluviatile synonyms from Bauhin and Haller 

 applicable to E. Telmatcia. Ehrhart in 1783 2 clearly pointed out 

 that E. fluviatilc and E. limosum of Linnaeus were branched and un- 

 branchcd fcrms of the same species and formally united them, un- 

 fortunately, however, giving to the aggregate the new and wholly 

 needless name E. Heleocharis. Ehrhart's union of E. limosum and 

 the real E. fluviatile has been accepted by the majority of authors 

 since, 3 though the name fluviatile long continued to be applied in 

 various works 4 to E. Telmatcia. Roth in 1800 (Tent. Fl. Germ. iii. 

 9) correctly united the two under the name E. limosum, citing as 

 synonyms E. fluviatile and E. Heleocharis, though, curiously, he took 

 the branched form as typical and made a varietal name for the true 

 typical form. A few authors, especially among the Scandinavians, 

 have employed the name E. fluviatile for the united species, but G. 

 F. W. Meyer, in 1836, 6 seems to have been the first formally to 

 reduce E. limosum to varietal status under it. 



It appears, then, that Roth was the first to unite E. limosum and 

 E. fluviatile under a tenable name and that, according to the Inter- 

 national Rules, the name which he chose, E. limosum, must stand. 



As stated by Eaton 6 there appear to be no true varieties of this 

 species in America. Its variants, though often striking in aspect, 

 not only intergrade freely, but occur commonly in the same colonies 

 throughout a similar range and sometimes even on the same rootstock. 

 Meyer and Milde considered the simple and branched forms as 

 seasonal states or due to the depth of water in which they happened 



« Fide Vaucher, Monog. des Pr&es. 45 (1822); Mllde, Monog. Equiset. 256 (1865); 

 Jackson, Index to the Linnean Herb. Proc. Linn. Soc., no. 124, Suppl. 72 (1912). 



' Hannov. Mag. (1783), Stueck 18, 286, according to Roth, Beitr., ii. 158 (1788). 



' See, for instance. Schkuhr, Krypt. Gew. t. 171 (1809) where both are figured on 

 the same plate under the name E. limosum. 



« Mildo, Monog. Equiset. 257 (1865) gives a long list of them. 



'Chloris Hanov. 668 (1836). 



•Fern Bull., x. 73 (1902). 



