96 J. O. HAGSTRÖM, CR1TICAL RESEARCHES ON THE POTAMOGETONS. 



— The colour of the leaves is ahvays lively green, often with a yellowish tone, just 

 as in the foregoing and the following (P. panormitanus). 



Distribution. Sweden, not common. Sednia, Råbelöfsjön, 84, Tedin (hb. Lund.) ; 

 Köpingeån, 76, Ljungström & Humbla (hb. Stockholm, Uppsal., Lund.); Höj, hb. 

 E. Fries (hb. Uppsal.); Höjeå. hb. Ag. (hb. Lund.); Lillsjön at Krageholm, Duben 

 (hb. Lund); Malmö in the channel at the railroad, 61, C. A. W. : Vejle lake, Duben 

 (hb. Lund.), 81, Wallengren (hb. Stockholm.); Nybro, 08, Jönsson (hb. L. M. 

 Xkuman). — Ostrogoihia, Roxen (hb. Stockholm.). — Gothland, near the church of 

 Sanda, 53, Westöö (hb. Uppsal.). — Sudermania, Eskilstuna, Hn. (hb. Stockholm.). 



— Stockholm, several stations (hb. Stockholm., Uppsal., Lund., Gothenb.). — Upp- 

 land, Skeboån, 67, Mosén (hb. Uppsal., Lund., Gothenb.); Sätuna, 46, Afzelius 

 (hb. Uppsal., Lund.); Metsjön, 81, Tiselius (hb. Stockholm., Uppsal.); Tranbygge 

 mill-river, 81, Tiselius (hb. Stockholm., Uppsal., Lund.); Valloxen, 81 Tiselius (hb. 

 Stockholm, Uppsal., Lund.); Sigtuna, Viby, 80, Floderus (hb. Uppsal.); Norrtelje- 

 viken (hb. Stochholm.); Uppsala at Falebro, 20, hb. Wahlenberg (hb. Uppsal.); 

 River at Haga, 51, Zdt (hb. Uppsal.). — Gestricia, Gefle, the south Lilla, 48, Hart- 

 man (hb. Uppsal.); Islandsån, 64, Thedenius (hb. Stockholm, Uppsal.); River at the 

 southern wharf, 35, Thedenius (hb. Uppsal.), f. borealis m. - — Helsingland, Söder- 

 hamn, 47, Svedberg (hb. Uppsal.), the most northern locality of Sweden, on 61° 15' 

 lat. bor. 



Norway, Drammen, Blytt in hb. E. Fries (hb. Uppsal.); Skien, Blytt (hb. 



Uppsal.). Denmark, several stations (hb. Stockholm., Uppsal., Lund.). — Finland, 



Alandia, Geta, Bolstaholm lake, 01, Palmgren & Klingstedt (hb. Stockholm.). 



Germany, several stations in Silesia, Brandenburg and Holstein (hb. Stockholm., 



Lund.). — England on several stations (hb. Stockholm.). 



North America, Manistee, Mich., 80, Hill (hb. Stockholm.); Perry, N. Y., 82, 

 Hill, and Geneva, N. Y., 84, Morong (hb. Stockholm.); Nov. Angl., Tuckkruw 

 (hb. Uppsal.); Aux Becs Scies, Mich., 80, Hill (hb. Stockholm.); Hastings County, 

 Canada, 74, Macoun (hb. Stockholm.). The northern limit of this species in Europé 

 and America may be the year-isotherm of +4° C. How far to the south it extends 

 is not fully known, at the most to the year isotherm of + 15° C, or perhaps rather, 

 + 12° C. 



T. iniK ronaliis Sciir. x obtiisifolius AI. & K. (1*. seiiiifnictiis Ar. Bennbt 

 a|). ('< ii. Ki'. nkr, PotamogetonacesB 1907, 138, nomen solum; Asm. & Ge., Syn. mittel- 

 eur. Fl., L> Aufl. 1913, 585, as obtusifol. Frieaii?). 



In Dr. C. J. Hartman's herbarium (hb. Uppsal.) I have fouud some speeiiuons 

 which must be referred to this hybrid. The leaves are in general like those of 

 r. obtusifolius and brown-ooloured, but pari- of them have the apex of a nmcronatus- 

 leaf. Ligules greenish and bicarinated as in /'. mucronat/us. 



Other specimens, collected by J. II. Wallman at Linköping and by E. Eriks 

 in Herb. Norm. V, si distributed under the name of P. dbtusifolius v. lacustris» have 

 an unusual searce ramifioation, especially in the spike-region, lighter colour Bhading 



