180 J. O. HASSTBÖM, CKITICAL RESEARCHES ON THE POTAMOUETONS. 



»P. fl tutans; P. oblonyus see. Fries.» On the contrary the specimens from »Eke- 

 berg», coll. 1854, C. A. W (= C. A. Westerlund), Haetm. Handb. Skand. Fl., 

 12th ed., 1889, 45, are P. polygonifolius v. amphibius Fries. Goihland, several sta- 

 tions: Fleringe and Bunge, the nothernmost localities of Europé, Kute, Westerhejde, 

 Ardre, Bäl etc., gathered by different collectors, the oldest specimens by Lönnroth, 

 1853, and Elmquist also in 1853 (hb. Stockholm., Uppsal., Lund. et Gothob.). 



Denmark, many stations in the islands; locus classicus is »Öxemose prope Hof- 

 mansgave Fionise, ubi primum in venit celeberrimus M. Vahl»: Hofman Bång in hb. 



— England in Kent, Cambridgeshire, Norfolk, Yorkshire and westward in Hereford- 

 shire (hb. Stockholm., Uppsal., Lund.). — Holland, (see Vuyck, Revisie etc. 1895!). 

 Belgium, Tirlemont, Thielens (hb. Stockholm.), Middelkerk, Crépin (hb. Stockholm.). 



— Germany: Hannover to Baden (hb. Stockholm., Uppsal., Lund.). — Switzcrland, 

 Geneva, Ayasse (hb. Uppsal., Lund.), Oerlikon, 81, Buser and others (hb. Stock- 

 holm., Uppsal., Lund.). — Austria, Moosbriinn (Nieder Öst.), 76 Wiesbaur (hb. 

 Stockholm., Uppsal.), Bohemia, Lissa, Celakovsky (hb. Lund.), Hungary, Altofen, 

 Steimtz (hb. Lund.). — Greece, according to Graebner, Potamog. 1907, 69 (not 

 1912). — France, many stations (hb. Stockholm., Uppsal., Lund.). — Spain, Ojos 

 del Guadiana (La Mancha), 83, Nilsson (hb. Uppsal.). — Kaly, Genoa, 42, Deiio- 

 taris (hb. Stockholm., Lund.), Sardinia, 81, Reverchon (hb. Stockholm., Uppsal., 

 Lund.), Sicily, leg. Lojacone (hb. Stockholm.) and Citarda (hb. Stockholm.). 



The species is also recorded from North Africa (Algeria), Aräbia and Australia, 

 but I have not seen specimens from there. Noriveqian specimens (Arendal: Blytt, 

 1897) are undoubtedly mistaken for P. polygonifolius Pourr. 



As is shown above the distribution area of this species is, on the whole, the 

 same as that of P. polygonifolius but it does not spread so far towards the north 

 and westward, and seems also to choose a more calcareous ground (ef. the occurrence 

 of the two species in the Scandinavian peninsula!). 



P. COloratus Vahl x polygonifolius Pourr. (P. anglicus n. hybr.). 



Folia submersa sat longe petiolata; natantia subcoriacea, ad nervaturam ut 

 in /'. colorato. Color ad basin caulis rufus ut in P. polygonifolio. 



Although /'. coloratus and polygonif. are so closely connected one to anothcr, 

 yet nobody has observed any crossing between them. Sonic specimens from Woking 

 llcath in Surrey, Kinjland, gathered by Ar. Bknnktt in 1881, however, secm to me 

 in all probability to be Buoh a bastard. The colour is reddiah; Bubmersed leavea 

 pretty Long-petioled ; floating leaves scarcely coriaceous; ligulea rather long (influenoea 

 from /'. polygonif.). On the other hand the nervation of the floating leayea reeemblea 

 that of l\ coloratus w it h more distant longitudinal aerves. Of all specimens from 

 different eountries I have scen, t hese are the only ones ocenpying a position (hat 

 makes me presumr a hybrid Origin. Yet I OUgbt to add that I have not seen /'. rolo- 

 ratus from any place in Suney, but it is growing in the neighbouring Kent (see 

 above!). 



