Potamacese. 
359 
— Ls oblong-elliptic, 45— lb mm long, rounded at the base, 
not clasping, almost smooth at the edges. P. lucens- 
perfoliatus?—As before; Geneva, Aarau. 6 
*decipiens Nolte. 2045. 
11 (2). Ls clasping the stem -with their bases like sheaths 12 
— Ls without sheaths ...... IS 
12. Carpels 8—4 mm ; almost half-circular, keeled. Like 2052, 
but ls with distinct lateral nerves. —As the last; distrib. .7 
pectinatus L. 2046. 
— Carpels smaller, obovate, almost globular, not keeled.— 
Alpine lakes, rarely lower; Chur, Engadine, Fully, 
Schwarzsee, Thun, Interlaken, lac des Rousses. 7 
marinus All. 2047. 
13. Stems and branches compressed-winged. Ls (3 —bmm 
broad) finely multinerved, with 3—5 more prominent 
nerves ........ . 14 
— Stem and branches cylindric, or compressed with rounded 
angles. Ls ( X/ 2 —3 mm broad) with 1—5 nerves . IS 
14. Spikes cylindric, composed of about 10—25 As, long- 
peduncled; peduncle 2—3 times as long as the spike. 
P. zosterifolius Schumch.—Stagnant or slow-flowing water, 
rare; lac des Rousses, lac d’Etalieres. 6 compressus L.2048. 
— Spikes ovoid, composed of about 4—8 fls, shortly ped- 
uncled; peduncle about as long as the spike. PI. denser. 
As the last; Wall.? french Jura. 6 acutifolius Link. 2049. 
15. Peduncles as long or hardly longer than the spike; 
spike dense, composed of about 6—8 fls. Ls obtuse or 
short mucronate.—As the last; rare or overlooked; lac 
d’Etalieres. 6 . . . . obtusifolius M. K. 2050. 
— Peduncles much longer than the spike; spike lax or 
rather so when mature ...... 16 
16. Stem almost quadrangular-compressed. Stipules 2-fid. 
Ls 2—3 mm broad. Peduncles slightly thickened towards 
the top. P. Oederi W. Mey., P. Friesii Rupr. ? P. pu- 
sillus major Koch.—As the last; on account of con¬ 
fusion with the following, the localities have still to be 
verified; lake of Zurich (Rchb.). mucronatus Schrad. 2051. 
— Stem almost cylindric. Stipules entire. Ls V 2 —2 mm 
broad. Peduncles filiform. P. Berchtoldi Fieb.—As the 
last; probably distrib. 6 . pusillus L. 2052. 
533. Zannichellia. Zannichellia. XXI, 23. 
1. Stem and ls filiform.—b. tenuis Beut. Ls finer, carpels 
only half the size. (Between Genthod and Versoix.)— 
Stagnant or slow-flowing water; distrib. but not com¬ 
mon. 6.palustris auct. 2053. 
