POTAMEvE. 



347 



4. spatulatns. Edges of Fr. acute. Sub- 

 mersed L. very attenuate into a long stalk. 

 Floating L. ovali-oblong, protracted at the 

 base. p. 7j 8. Clear streams. Kaisersleu- 

 teu and Zweibriicken. Bitche, Lorr. 



5. planta^ineus. Edges of Fr. obtuse. 

 All L. stalked and membranous, smooth, on 

 margin. Submersed L. lanceolate. Floating 

 L. somewhat cordate. Spike-stalks cylindrical. 

 p. 7, 8. Stagnant. Westphalia. Rhine. 



ii. Loioer L. permanent ; upper floating, not 

 always present till late in the summer. 

 Mower-stalks from both. 



6. riifescens. Edges of Fr. acute. Sub- 

 mersed L. lanceolate, sessile, somewhat obtuse. 

 Margin smooth. Floating L. somewhat coria- 

 ceous, obovate, tapering into a stalk shorter 

 than itself. Spike-stalk cylindrical, p. 7, 8. 

 Still water. G. 



7- variifolius. Submersed L. lineari-lan- 

 ceolate, somewhat cuspidate : margin smooth. 

 Floating L. lanceolate, tapering into stalk. 

 Spike-stalk cylindrical, p. 7. Streams. Gasc, 

 Thore. Quimper, J. W. 



8. lanceolatus. " Submersed L. lanceo- 

 late, sessile, narrowed at both ends, entii'e, not 

 apiculate. Floating L. somewhat coriaceous, 

 elliptico-lanceolate. Stip. lineari-lanceolate, 

 acute ; uppermost broader. Fr.-stalk cylindri- 

 cal. Submersed L. with chain-like reticula- 

 tions near the midrib, p. 7, 8. Small streams. 

 Anglesea. Sc." — Bab. 



9. heterophyllws. Edges of Fr. obtuse. 

 Submersed L. lanceolate, margin I'ough ; lower 

 sessile. Floating L. ovate or lanceolate, on 

 long stalks. Spike-stalks thicker upwards. 

 Lower L. lanceolate, recurved, p. Still 

 water. G. 



;8. graminifolius. Lower L. lanceolato-li- 

 near, attenuate at both ends. 



7. Zizii. Much larger than the preceding. 

 L., especially the upper, obtuse, mucro- 

 nate. Margin undulate. 



10. nitens. Fr. keeled when di-y. Sub- 

 mersed L. rounded at base and semiamplexi- 

 caul ; rough on margin. Floating L. elliptic, 

 attenuate. Spike-stalk somewhat thicker up- 

 wards, p. 7, 8. Still, n. G. 



a. salicif alius. Submersed L. lineari-lan- 

 ceolate, straight. 



j8. heterophyllus. Submersed L. lanceo- 

 late or ovato-lanceolate, recm'ved. 



11. augustanus. " Lower L. broadly lan- 



(icolate, stalked ; upper lineari-lanceolate, ses- 

 sile, acuminate : all pellucid, 5-7-nerved, and 

 veiny. Spike on a very long stalk, p. 7, 8. 

 Aosta." — Bert. Koch unites this to hetero- 

 phyllus ;/ro?« which, however, and all others, 

 it seems essentially to differ, in its hroad and, 

 stalked lower L., and narrower sessile upper. 

 It is not clear from Bert, that it has any 

 floating L. 



H. All L. submersed. Floral L. opposite ; 



all others alternate. 



i. L. lanceolate or broader. 



12. iucens. Edges of Fr. obtuse, with a 

 slight keel. L. stalked, lanceolate, cuspidate. 

 Margin rough. Spike-stalk thickened up- 

 wards, p. 7, 8. Water. 



13. lon^ifolius of Gay. " L. pellucid, 

 long lanceolate, narrowed below, quite entire, 

 apiculate. Stip. winged. Fr. imknown. Spike- 

 stalk very long, swelling upwards. Spikes 

 with a few subverticillate distant flowers, p. 

 8. Deep loater. Loch Corrib." — Bab. 



14. siculus. " L. oblongo-lanceolate, at- 

 tenuate at each end, stalked ; lower alternate : 

 all smooth on margin. Stip. intrafoliaceous, 

 amplexicaul, acute. Spikes and StaUis slender. 



p. 5, 6. Pools. 

 Guss. 



Stalks much exceeding L. 



2 y 



Gurgo di Caccaci." 



15. decipiens. L. all pellucid, ovate or 

 oblong, rounded at base, sessile, mucronate, 

 not hood-like at top. Margin smooth. Spike- 

 stalks cylindrical. Fr. unknown, p. 7, 8. 

 Rivers. Hamb. Hoist. 



16. prselongus. Fr. with a winged keel. 

 L. oblong or lanceolate, rounded at base, am- 

 plexicaul, hooded at the tip, obtuse -. margin 

 smooth. Spike-stalk cylindrical, p. 7, 8. 

 Still, n. G. Sw. Cam. Eng. 



17. perfoliatus. Edges of Fr. obtuse. 



L. cordato-amplexicaul, rough on margin, p. 

 7, 8. Ponds and rivers. 



18. crispus. Fi'. compressed, rostrate. (L. 

 lanceolate, rather obtuse, wavj% serrate, Sm.) 

 (L. linear-oblong, obtuse, with acumen, Koch.) 

 Spike-stalks cylindrical, p. 6, 7. Water. 



ii. L. linear or narroioer, sessile. Stem much 



branched. 



a. Stipules separate from leaf. 



19. acutifolius. Stem compressed, winged. 

 L. cuspidate, with 3-5 parallel nerves and nu- 

 merous liner intermediate ones. Spikes subro- 

 tund, 6 -flowered, nearly ais long as stalk, p. 

 7, 8. Still water. G. occ. s. Eng. 



2 



