184 J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



P. cmiariensis Link in Buch, Beschreib. Canar. Inseln, 1825, 138. — P. Leschenaultii 

 Cham. & Schlecht. in Linnsea, 1827, 223? — P. occidentalis Siebek ap. Cham. & Schl., 

 I. c. 224. — P. americanus Cham, et Schl., 1. c, 226. — P. syriacus Cham. & Schl., 



I. c, 227. — P- mascarensis, P. marianensis, and P. owaihiensis Cham. & Schl., 

 ]. c, 228. — P. petiolatus Wolfg. ap. Schultbs, Mantissa in vol. Ill etc., 1827, 252. — 

 P. Roxburghianus Schultes, 1. c, 367? — P. Besserl Steudel, Nomenclator ed. 2, 



II, 1841, 384? — P. Billotii Schultz, Archives de la Fl. de France et d'Allem., I, 

 1842, 61. — P. lonchitis Tuckerm., Observations etc. in The Am. Journ. Sci. and 

 Arts, 1848, 226. — P. fluitans (Roth) RAUNKiJiiR, Anatom. Pot. Studies etc. in Bot. 

 Tidskr. 1903, 271—280. — Fig. 1, C, 95. 



By the earlier authors, Koch, Gatjdin etc., and quite up to later times (Buche- 

 NAXj), this species has been mixed up with P. nutans L., and placed as a variety under 

 that species (P. natans p explanaius Meet. & Koch, 1823, 837 — 838, etc.). Other 

 authors, separating it true enough from P. natans, have commingled it with some 

 hybrids under the name of P. fluitans Roth. Thus P. Graebnee, who, although 

 distinguishing between fruiting and sterile forms, yet looks upon them all as »einheit- 

 liches Ganzes» (Lebensgesch. etc. 1906, 435; so still in Synopsis, 1912, 464 sq.) 

 possibly of hybrid origin. With this view the name P. fluitans can be said to be 

 the only correct name for those forms. C. Raunki^e has by means of specimens 

 determined by Roth tried to prove that the name P. fluitans only is due to the 

 fruiting plant, which under a great number of names, but first by Poieet, has been 

 described. This proof would be very strong, if those specimens examined also really 

 corresponded with the original description by Roth »foliis inferioribus longissimis» 

 etc. (Tentara. Fl. Germ. I, 1788, 72), which they can scarcely be said to do. Nor 

 has Raunki^r tried to show that. Rather this description answers to the hybrid 

 lucens X natans, which more often than P. nodosus has very long and always more 

 durable submersed leaves. Only in very rare cases P. nodosus has leaves of a foot- 

 length or more. Strange to say G. Fischer, however, finds this description adequate 

 to the fruiting plant when writing, »Ware nur die erste Publikation Roth's v. J. 1788 

 vorhanden, so wiirde ich nicht das mindeste Bedenken tragen, der Art den Namen 

 P. fluitans Roth zu belassen. Denn die kurze Beschreibung stimmt dazu.» On the 

 other hand the same author is of the opinion that Roth's second and more detailed 

 description contains more characteristics not at all agreeing with the plant, looked 

 upon as a true species, but referable to a hybrid. Fischer, therefore, writes in 

 1907, »P. fluitans (Roth? Rchb. p. p.) Koch, s. str. F.», a mode of signifying, which, 

 probably, will not gain adherence. Seven j^ears later he writes: P. fluitans Roth, 

 and divides it into two parts: Proles (vel sectio, series) I. P. Rothii Fischer, and 

 Proles (vel sectio, series) 11. P. Raunkiceri Fischer, the latter »= P . natans x lucens 

 sec. Raunk., Hagstr. »^ (Bemerkk. zu den Potamogetoneaj etc in Mitt. Bayer. B. 

 Ges. 1914). Farther below, on the same page, he notes, »Meine Vollmannsdorfer 

 Exemplare sind — sicher P. lucens X natans und sollen den Namen P. Harzii 



^ RAUNKia:E and Haqstrom write P. lucens X natans. 



