136 P* Graebner. — Potamogetonaceae. 



perfectae neque adhuc fixam formam nactae sint. Eodem loco, ubi auctor hanc plantam 

 legit, multitudinera vidit formarum, in quibus formae expositae i conjunctae sunt. Forsitan 

 sit haec planta forma hybrida inter P. gramineum et P. nalantem, quae nondum tantum virium 

 adepta sit, ut flores apertos et fructus proferre possit. Ex cl. Tiselio 2 formae distingui possunt. 



Var. er. pergramineus Aschers, et Graebner 1. c. (1897). — Forma P. gramineo 

 proxima. — Forma intermedia est intermedius Kupffer 1. c. (1906). 



Var. ß. pernatans Aschers, et Graebner 1. c. (1897); Kupffer, Korresp. bl. Naturf. 

 Ver. Riga IL. (1906) 170. — Forma P. natanti proxima. 



P. gramineus X perfoliatus Hagström in Neuman, Sverig. Fl. (1901) 796. 



Schweden. — Cl.. autor distinguit 3 varietates: a. subgramineus (conf. etiam 

 Mühlen et Kupffer in Korresp. bl. Naturf. Ver. Riga IL. [1906] 170, 171) — ß. sub- 

 perfoliatus — y. intermedius. — Ex cl. auctor interdum cum P. gramineus X per- 

 foliato mixtus et huc pertinent formae diversae a cl. Tiselio sub P. nitens citatae. 



P. gramineus X polygonifolius. — P. polygonifolius X gramineus (P. Seemenii) 

 Aschers, et Graebner, Synops. mitteleurop. Fl. I. (1897) 335. — P. gramineo sub- 

 similis sed major et folia inferiora submersa spathulata, basi in petiolum elongatum 

 attenuata, omnia statu sicco rubescentia. 



Europa: bisher nur auf Borkum: Kievietsdelle (O. v. Seemen!). Schweden 

 (Hagström in Neuman, Sverig. Fl. [1901] 797). Die übrigen Angaben stellen wohl 

 Formen des P. gramineus dar. 



Nota. Planta certissime hybrida inter parentes est, nam folia submersa petiolata spathu- 

 lata nunquam in P. gramineo occurrunt. P. polygonifolius X heterophyllus Beeby n. 1077 in 

 Herb. Kew mihi forma P. polygonifolii tantum esse videtur = f. [caneellatus Fryer, Pot. Brit. 

 Isles. [1898] 21. sub polygnifolio). Cl. Hag ström distinguit 1. c. f. lanceolatifolius Tisel. 



P. gramineus X praelongus [P. graminea X praelonga) Almquist in Hartman, 

 Handb. Skand. Fl. 12. uppl. (1889) 49. — P. Lundii Richter, PI, Eur. I. (1890) 13 

 nomen nudum. — P. praelongus X gramineus Aschers, et Graebner, Synops. mittel- 

 europ. Fl. I. (1897) 330. — P. praelongus X heterophyllus — gramini / blius A. Bennett 

 in Journ. of Bot. XLII. (1903) 166. 



Europa: südliches Schweden, östliches Smäland (Lund). In England zweifelhaft 

 (conf. A. Bennett 1. c). 



P. gramineus X pusillus Aschers, et Graebner, Synops. mitteleurop. Fl. I. (1897) 

 3 48. — P. rivularis Gillot in Magn. Scrin. VI. (1887) 118; Bull. Soc. Dauph. XIV. 

 (1887) 584; Herb. p. pt. ex A. Bennett in Bull. Herb. Boiss. III. (1895) 257; Fryer 

 in Journ. of Bot. XXXII. (1894) 337. — P. heterophyllus X pusillus, P. lanceolatus 

 var. rivularis Fryer 1. c. (1894) 338. — P. rufescens, P. rivularis Nym. Consp. Suppl. 

 (1890) 287. 



Europa: bisher nur in Frankreich: Montemerle, Saöne et Loire (Gillot). 



Nota. Planta valde singularis. 



P. gramineus x Zizii conf. P. spathuliformis p. 91. — P. varians Fryer in 

 Journ. of Bot. XXV. (1887) 308, XXVII. (1889) 33 t. 287 etiam Morong in litt. — 

 P. lieterophyllus var. fluctuans Tisel. (conf. p. 88) ex cl. Fryer in Journ. of Bot. XXVIII. 

 (1890) 174 forsan est hybrida inter P. gramineum et Zizii. — P. Zizii X hetero- 

 phyllus A. Bennett m Journ. of Bot. XXX. (1892) 117 (p. pte. ?) — P. Zizii X gra- 

 mineus Aschers, et Graebner, Synops. mitteleurop. Fl. I. (1897) 327 (p. pte.?). 



Europa: Schlesien; Bheinprovinz. England! Schweden. 



Nordamerika: die Angaben aus Nordamerika beziehen sich schwerlich auf diesen 

 Bastard, sondern auf den noch etwas unklaren P. spathuliformis (vergl. p. 91). 



Nota. Hybrida valde variabilis, nunc formas pergramineus nunc pei--Zizii producit. 

 Fryer in Journ. of Bot. XXVIII. (1890) 176. 



P. lucens X natans. — P. Noltei Fischer in Mitt. Bayr. Bot. Ges. München 

 XXXVII. (1905) 472; Mühlen et Kupffer, Korresp. bl. Naturf. Ver. Riga IL. (1906) 171 

 nee A. Benn.; Fischer in Ber. Bayr. Bot. Ges. XI. (1901) 55. — P. fluitans conf. 

 p. 58 ff. 



