POTAMOGETON. 
353 
stipules have two prominent wings on their back. Spikes long, 
about equalling the peduncles. Mr. W. Wilson found "ovate- 
lanceolate moderately acute coriaceous 1." When the limb of 
the 1. is much reduced in size and the midrib prominent and 
resembling a long spine, it is the P. acuminattts Schum. — Common 
in deepish water. P. VI. E. S. I. 
9. P. loiif/ifdlius (Gay ?) ; I. pellucid long -lanceolate narrowed 
below entire cuspidate, stip. winged, fi- , peduncle very 
long swelling upwards, spikes vidth few rather whorled distant 
flowers.—^. B. S. 2847. — St. long, slender. L. distant, not 
denticulate, nearly sessile with very short .stalks. Stipules green, 
lanceolate, with 2 narrow wings on the back. Ped. 6 — 8 in. 
long, much thicker than the stem. Spike about an inch long ; 
fl. rather more whorled than as represented in MB.S. Fr. 
unknown. — Deep water. Lough Corrib, Galway. 3fr. J. Ball. 
P. VIII. I. 
10. p. prcslon'gus (Wulf.) ; Z. pellucid ohlong-lanceolate half- 
clasping blunt and hooded at the end entire, stip. not winged, fr. 
rounded (rarely keeled) on the back when fresh heeled or winged 
when dry, peduncle very long equal, spikes many-flowered. — 
E. B. S. 2858. R. vii. 3.3. — St. long, growing in deep water. 
Peduncles 6 — 12 in. long. Spikes 1 — 2 in. long. — Rivera and 
ditches, rare. P. VI. E. S. I. 
11. P. perfolidlm (J,. ; st. round, I. pellucid cordate-ovate 
clasping not hooded, fr. rounded on the back when fresh keeled 
when dry, peduncle equal. — E. B. 168. R. vii. 29. — St. long, 
slightly branched. Peduncles rather thick and short. Spikes 
short.-^Lakes and sti-eams. P. \TI. E. S. I. 
12. P. cris'pus (L.) ; st. compressed, I. -^qQmc'A linear-ohlong 
blimt sessile sen'ate wavy, fr. ivitk a long heak keeled on the 
back when dry, peduncle equal.— ^. B. 1012. R. vii. 29—30. 
— St. much branched. Ped. long. Spikes few-flowered. Beak 
as long as the nut. L. usually crispea at the edges, occasionally 
flat (P. serratus Huds.). — Ditches and streams. P. VI. E. S. I. 
*** L. all submersed, alternate, linear! stipules free. 
13. P. zosterifolius (Schum.) ; st. flattened, I. lineai'-acumi- 
nate with 3 principal and many close parallel intermediate veins 
occupying the whole surface, spikes cylindrical upon long ped., 
sep. transversely oval, fr. obovate keeled, style terminal. — 
E. B. S. 268-5. R. vii. 27. P. cusjndatns Sm., P. conipressus 
Fries. — Ped. 2 — 4 in. long. Spikes 10 — 15-flowered. Inner 
edge of fr. rounded ; faces a little convex. L. suddenly acumi- 
nate or apiculate. — Rivers and lakes. P. VI. E. S. I. 
14. P. acutifdlius (Link) ; st. flattened, I. linear acuminate with 
