66 J. O. IIAGSTRÖM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



Further, f. minor, with short internodes and small leaves; f. latifolius, broad-leaved; 

 f. angustifolius narrow-leaved; f. euspidatus with elongated, finely cuspidate leaves. 

 Probably he means a form called by J. Baagöe (in some herbaria) »f. cuspidala 

 which on closer investigation has turned into the X P. bambergensis; f. selpnooarpus, 

 fruit inside with a basal boss as in P. acutifolius. It may be added that a micro- 

 carp form is also found. 



A form hitherto not studied is the above mentioned abortive form, f. abortivus m. 

 It has ahvays abbreviated peduncles (15 — 25 mm), undeveloped spikes with only 5—7 

 verticils and barren flower parts. It behaves completely as a bastard and it is not 

 impossible that the properties just now mentioned may derive their origin from P. 

 acutifolius. If this were the case the reduced number of the middle vascular bund- 

 les of the peduncle also would be satisfactorily explained. In the vegetative parts, 

 however, no influence from P. acutifolius can be traced, but it is possible, that fu- 

 ture researches here also may discover what we at present are unable to discern. 



I have seen distinct examples of this interesting plant from Sweden, Uppland 

 in the following small lakes or water currents: Metsjön in Fasterna, 82, Tiselius 

 (hb. Stockholm, et Uppsal.), Sparren in the parish of Närtuna, 93, Tiselius (hb. 

 Stockholm, et Uppsal.), Valloxen 82, Tiselius (hb. Stockholm, et Uppsal.), Heder- 

 viken, 58, Tiselius (hb. Uppsal, et Lund.), Bergshamra in Kyrksjön, 78, Löfgren 

 (hb. Lund.), Skeboån, 67, Mosén (hb. Uppsal., Lund. et Gotenb.). — Sudermania, 

 for instance in Bränningeträsk near Södertelje, and in Tumba kvarnsjö. On the oc- 

 currence of the supposed parent-species in those regions, see below ! 



But a similar plant is also collected in Scotland by Babington (hb. Stockholm, 

 et Uppsal.), where P. acutifolius is not now met with. Nevertheless it is possible 

 that it has occurred there in oiden times. 



P. zoslerifolius has an amphigean distribution. Sweden northwards to east 

 Jemtland, Barrsjön, 81, Tiselius (hb. Stockholm., Uppsal, et Lund.), f. major, and 

 south Angermania, Gudmundrå at Frånö, 70, Sjöstedt (hb. Stockholm.) ca. 63° N. L. 

 To the south of this point it has an eastern distribution through Medelpad, Selänger 

 near Sundsvall, 24, L.estadius and others (hb. Stockholm., Uppsal, and Lund.), f. 

 anguslifolius, fruiting; Gestricia, Trösken at Gefle, 65, Theel and others (hb. Stock- 

 holm., Uppsal, et Lund.); Uppland, many stations, for instance Norrsjön at Blad- 

 åker, 02, Uingselle (hb. Uppsal, et Lund.), Lomaren at Norrtelje, 80, Hedlund 

 (hl). Uppsal.), Sätrasjön at Uppsala, 28, Wahlbnbsbg (hb. Uppsal.), Ekebysjön, 18, 

 Wahlbnbebg (hb. Uppsal.), Fyrisån, 28, Wahlbnbebg (hb. Uppsal.); Westmanland, 

 Köpingeån, 48, »Lhtr» (hb. Uppsal.); Sudermania, many stations, tor instance at 

 Stockholm, collected by Nyman, HäBTMAN, Thbdenius and others (hb. Stockholm., 

 Uppsal, et Lund.), Nyköping, 51, Fbistbdt (hb. Stockholm.), Eskilstuna, 83, Pbhbs- 

 BOS (lil). Lund.), Årdala, 50, Fbistedt (hb. Uppsal.) etc; Nericia, [geln in the pa- 

 rish of Sköllersta, 70, HABTMAN (hb. Uppsal.), at Örebro, 00, EABTMAB and låter 



many others (lil>. Uppsal, et Lund.); Ostrogothia, Norrköping, ."»o. Hammabsten and 



others (hb. Uppsal.), Himmelstalund, 07, Elmqvist (hb. Lund.). Söderköping, 49, 



Lbo (IiO. Uppsal.), Linköping, 24, Fribs (hb. Uppsal.), Skrukeby and Svinstad, 



