236 



J. O. HAGSTRÖM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



Fig. 110. A — C, P.lucena L. A, Leaf-margiu, 

 showing the dentiealation and fche Binns between 

 two dentioles, enlarged. /■', Transverse aection "i 

 pari of the lignle al the base, ","■ showing the 

 itrnctnre and the heighl <>f the ridge in relation 

 to the thickness ol the intercarinal part, le. /■'. 

 and 67, corresponding parte of /'. gramineus X 

 lucen» (/'. /.i .a .M . K.) and /'. gramineus I.. to 

 ihow tii- intermediate position oi t >■<- former, '', 

 1'istil, -/, yide-view, /<. stigma from above, \". I> 

 / /' lucen I.. \. longifulius DC. D, Basaland 

 ' pari "t a t. m i. af, j /■/, Baeal and apical 

 pari "i | branch-leaf, |. /•', P. gramineus A lucen» 

 (P /.* Ii M K.), transversi soction of lignle, ;c- 

 iii /(. *,", Q—H, P. graminen» L. O, Transv. aect. 

 '>( lignle, as in //. ",■''■ ' l ' 1 " dotted line indicates 

 ■K' beighl "t the ridgi :>i the involncral leaves. 

 //, Leal margin, showing the dentiealation, i nlarged. 



with more or less abruptly cusp 



Loew, Schröter, Lebensgesch., 1906, 450, f. 254: 

 hybernating forms. — Fontell, Beiträge etc. 1909, 

 t, III, f. 80—83, t. IV, f. 90-91: anatomical 

 pictures of stem, rhizome etc. 



Distribution. Siveden, Scania and through 

 the whole country (hb. Stockholm., Uppsal., Lund., 

 Gothbg.) as far as Helsingland, Jerfsö, Kalfsjön, 89, 

 Schlyter (hb. Uppsal.), Medelpad (the valley of the 

 Ljungan and the Gimån) Borgsjön, 04, Ringius (hb. 

 Lund.), Torpsjön, 60, C. Rx (hb. Uppsal.), f. insignis, 

 Stödesjön, 05, Collinder, Mellansjön, 10, Nord- 

 ström, and East Jemtland, Holmsjön, 84, Tiselius 

 (hb. Stockholm.), Hällesjö, Håsjö, 64, Tiselius (hb. 

 Stockholm., Uppsal., Lund.) and Håsjö — Ragunda: 

 Mill-lake, 86, Sundberg, the most northern station 

 of Sweden, ca. 63° n. lat. with a year-isotherm of 

 about + 3° C. Consequently it is not observed in 

 Western Jemtland, Herjedalia, Western Helsingland, 

 West and North Dalarne and Wcrmhind. 



Norway, Hrersöen, Blytt (hb. Uppsal.), 

 Asker, Högstadtj. and Padderudsv., Hadel. (Jaren), 

 Hedern. (Stavsjö); besides in Jaideren, Söglandsv. (hb. 

 Christian.). - jF/H.Zawd,Tavastiaaustr., Rauntunselkä, 

 83, Granberg (hb. Stockholm., Uppsal., Lund.). 

 The statement in Hjelt & Hult, Vegetationen o. 

 Floran i en del af Kemi Lappmark etc. in Meddel. 

 Soc. Fauna et Flora fenn. XII, 1885, that P. lucens 

 occurs at Kolari, is no doubt a mistake (probably 

 for P. gramineus f. septentrionalis Tis. (Hagstr.)). 

 P. lucens is a much more southern species than P. 

 gnnnineus. In the Swedish Museums thcre are 



a great many specimens from Den mark, Enghmd, 

 France, German//, Auelria II ungar;/, Siritzcrland, 

 Itali/, Venetia, 78, RlOO (hb. Lund.), Herccgovina, 

 89, MuBBBOE (lib. Stockliolm., Uppsal., Lund.). 

 Lilhuania, Vilna (hb. Stockholm., Uppsal., Bremen.), 

 v. longif olivs: — Has long intemodes and short 

 branches; stém-leaves narrow and protracted 200 

 350 X 15 20 mm, short-petioled (10— 20 mm) and 

 with rather weak serrulation (foliifl integerrimis: 

 \\'«)i. r:., is misleading), bheir ligulcs 70 — 100 mm 

 long; branch-leaves likewise narrow, 12 — 15 mm, 

 idate apex, see the figure 110, tapering base, shorl 



