24 



P. oblongus. Koch /. c. p. 775. 



Hab. in Rossia media [ins. Osilia! (Meyer et Bunge pl. exs.)] inque S i biriae 

 altaicae deserto soongoro-kirghisico pr. Urdschar! (Schrenk pl. ex°s.). 4. 



3. P. fluitans (Roth Tentam. Fl.germ. I , p. 72; II, p. 202) 

 foliis omnibus ionge petiolatis; submersis sub antbesi persistentibus 

 elongato-Ianceolatis linearibusve membranaceis pellucidis; natantibus 

 coriaceis oblongo-lanceolatis ellipticisve basi ovatis v. rotundatis, pe- 

 tiolis supra convexis, pedunculis aequalibus. fructibus recentibus com- 

 pressis, inargine acutiusculo. 



P. fluitans. Koch l. c. p. 776. — Gkorgi Beschreib. d. Russ. R. III, 4. p. 746. 



— M. a Bieb. Fl. t. c. I, p. 117; III, p. 115. — Luce Fl. osil. p. 41. — 



Hofft Cat. liursk. p. 12. — Eichw. Skissxe p. 125. — Ruprecht in Beitr. 



x. Pftanxenk. d. Russ. R. IV, p. 42. 

 P. natantis var. foliis lanceolato-obiongis longius petiolatis. Sobol. Fl. petropol. 



No. 123 (ex M. a Bieb.). 

 Hab. in Rossia media [Petropoli (Sobolewsky, Rupf.echt), ins. Osilia (Luce), 



Lithuania ! (Eichw. , Wolfgang pl. e.vs.) , Volhynia (Eichw.), Kursk (Hofft)] 



et australi [Podolia (Eichw.) , ad Tanain (Henning)] inque Tauria (M. 



a Bieb.) et provinciis caucasicis [\lingrelia (Nordmann)]. 4- 



4. P. petiolnlus (Wolfgang in Schult. Mant. in Syst. Veg. III, 

 p. 352) caule tereti lluitante, foliis longe petiolatis; superioribus op- 

 positis natantibus subcoriaceis quintuplinerviis ovato-lanceolatis oblon- 

 gisve; inferioribus alternis latioribus ovato-lanceolatis subundulatis, 

 pedunculis terminalibus foliis brevioribus, spica elongata tenui. 



P. petiolatus. Eichw. Skisase p. 125. 



Hab. in Rossia media [Lithuania et Volhynia (Eichw.)] et australi [Cherson 

 in Borysthene fl. (Andrz. ex Bessep.)]. 4. 



„E majoribus. Folia superiora \ x / 2 — ^ poll. longa, 10 — 15 lin. 

 lata; petioli 2 — 3 poll." (Besser ap. Schult. /. c.) — An P. naten- 

 tis var. ? 



b. Folia floralia caulinis similia, seriora tantum natantia et v. 

 coriacea v. membranacea formaque (sed non in omnibus) diversa. 

 — Folia natantia saepe desunt. 



5. P. nerviger (Wolfg. in Schult. Mant. in Syst. Veg. III, 

 p. 359) caule tereti lluitante, foliis superioribus oppositis subnatan- 

 tibus ovatis utrinque acutis coriaceis nervigeris subpetiolatis integer- 

 rimis; inferioribus alternis oblongis v. ovato-lanceolatis nervosissimis 

 sessilibus subcoriaceis integerrimis , costa basi Jatissima , pedunculis 

 aequalibus compressiusculis. 



P. nervigerus. Eichw. Skitsze p. 125. 



Hab. in Rossia niedia [Lithuania in fl. Wierzchnia circa Lelany (Wolfgang, 

 Eichw.)]. 4. 



„E majoribus. Folia 4—6 poll. longa , 12 — 15 lin. lata , magis 

 crassa et rigida ac coriacea". (Besser ap. Schult. /. C.) — A P. 

 rufescente vix differre videtur. 



6. P. rigidus (Wolfg. in Schult. Mant. in Syst. Veg. III, p. 359) 

 caule crassiusculo tereti, foliis supremis binis oppositis subnatantibus 

 ovato-lanceolatis v. oblongis breve petiolatis snbcoriaceis acutiusculis ; 

 inferioribus alternis Janceolatis elongatis subpetiolatis utrinque attenua- 



