• '»2 J. O. HAGSTKÖM, CRITICAL RESEARCHES OX THE rOTAMOGETONS. 



Conspectus formarum : 



a.. Serrulatus: — Folia serrulata, in margine iis P. perfoliati similia. 



f. eu-Coopéri Graebner, Potamog. in Engler, Pflanzenr. IV; 11, 1907, 13-4. — 

 P. undulatus var. Oooperi Fr v er 1. c, tab. 313. 



Stem-leaves broad and elongated, usually 60—70 mm long by 20—30 mm in 

 width. A single station known: England, Leiceaterahire: Canal Loughborough. Thia 

 plant might possibly be P. crisp. X prcel. 



f. Jacksonii (Lbes). — P. perfoliatus var. Jackson i Lees in The Bot. Record 

 Club Report 1880, 150. — P. undulatus (crispus x perfoliatus) var. Jackson* (Lees) 

 Fryer, 1. c. 290—291: — Stem-leaves commonly of the size ," mm (45— 60 x 13—20). 

 In habit often very like P. perfoliatus L. 



Distribution. England, Chester, River Dee, 91, Billups (hb. Stockholm.), 

 Cambridgeshire, Parsonware Drove, Benvvick, 92, Billups & Fr ver (hb. Stockholm.). 



f. scoticus n. f. — Folia anguste ovato-lanceolata. — Stem-leaves norrower and 

 comparatively more elongated than in the precedent and following forms, 50 — 80 X 

 X 6—13 mm. 



Distribution. Scotland, Stirlingshire, Union Canal supra Falkirk, 94, Stirling 

 & Kidston (hb. Stockholm, et Lund.). 



p. Serratus: — Folia serrato-dentata. 



f. Fischeri n. f. — Folia caulina ca. 20 — 25 mm longa, 10 — 12 mm lata. — 

 P. cymbifolius Fischer, 1. c. 



Fischer parts his P. cymbif. into two forms: f. sub perfoliatus and f. subcrispus 

 yet without stating the separating diffcrences. All materials from Ebing I have seen 

 are uniform and I proposc to name the form af ter its meritorious discoverer Dr. 

 G. Fischer, Professor in Bamberg. 



Distribution. Germany, Bavaria, Mainaltung bci Ebing, 02, Fis< 1 1 1 : k (hb. 

 Stockholm.). 



Real P. Cooperi is besides observed by us from Gudcna in Denmark (hb. Baagöe). 



P. crfspns l. praelongus Wulf. 



Kx Caspaby, Berieht etc. in Schriften Phya. ök. Ge8. KÖnigeberg 1878, 9<i 98. 



— P. undulahis Wni.KC in ,J. A. å J. H. Sciin/rEs, Mantissa in vol. tcrt. etc. 1827, 

 360, ex I<aiinki^:r, Danske Blomsterpl. I, 1896, 104. 



Thia hybrid can easily be dislinguishcd both from the preceding bastard aml 

 [rom t lie parent-apeoiea in the bioanaliculate stem and the even leaf-margin. At lc;ist 

 bitherto very i«\\ individuala of it have been diacovered with mdimentary aerrature. 

 The author has scen a aingle apecixnen from Langer Sce of Wesf-Prussia. ()n ancb 

 individuala thoae dental rudimenta, at all eventa, ean be obaerved only in very young 

 leavea as thcy very soon disappcar. On the contrarv tlic Leaf margin ottcn appcars 



