PONDWEED FAMILY. 



75 



26. Potamogeton lateralis Morong. Opposite-leaved Ponclwced. ( } 



I'ntiimogeton lateralis Morong, Coult. Bot. Gaz. 5: 



51. 1880. 



Stems filiform, much branched. Floating 

 leaves on sterile shoots only, coriaceous, ellip- 

 tic, obtuse, 4 // -5 // long, i // -2 // wide, 5-7- 

 nerved, the nerves deeply impressed beneath, 

 usually in 1-3 opposite pairs which stand at 

 right angles to the stem, on petioles 3 // -io // 

 long; submerged leaves linear, acute, 1'-$' long, 

 ]^"-yt." wide, i-3-nerved, 2-glandular at the 

 base, but the glands small and often obsolete; 

 stipules small, hyaline, many-nerved, obtuse, 

 deciduous ; peduncles and floating leaves lateral, 

 with a peculiar appearance, widely spreading 

 at maturity, sometimes recurved, thickening in 

 fruit, 4 // -i5 // long; spikes capitate or often in- 

 terrupted, 3-4-flowered; fruit obliquely obovoid, 

 about i" long, lenticular, v the back much curved 

 and 2-grooved, the face arched and surmounted 

 by the nearly sessile stigma; curve of the em- 

 bryo oval, its apex nearly touching its base. 



In lakes and slow streams, eastern Massachusetts to Michigan. l'n.lifcr-u- shoot- .it tin- Com- 

 mit of the stem and on the upper branches appear late in tin- season, a- tin- plant- ar. 1 KimmK 

 decay. July-Aug. 



Potamogeton pusillus L. Small Ponchvecd. \V\. i6S.) 



Potamogeton pusilltu I,. Sp. I'l. 177. 



Stems filiform, branching, 6'-2 long. 

 Leaves all submerged, linear, obtuse and mu- 

 cronate or acute at the a]>ex, 2-glandular at the 

 base, \'-$' long, about N" wide, i-j-nerved, 

 the lateral nerves often obscure; stipule* short, 

 hyaline, obtuse; peduncles usually 3" 9", or 

 rarely 3' long; spikes 3-io-flowered; fru 

 liquely ellipsoid, about i" long and S" thick 

 curved and 2-groovcd on the backer sometime* 

 with 3 distinct keels, the face slightly arched, 

 beaked by a straight or recurved style; apex of 

 the embryo slightly incurved and pointing ob- 

 liquely downward. Preparative bud occur in 

 greater or less abundance. 



In ponds and slow stnai; 

 British Columbia, south to Viiw 

 California. Also in Hiiro]* July-AnC- 



Potamogeton pusillus Panormitanus (Biv.) Morong. Mem T>rr Club. 3: Part 

 Potamogeton Panormitanus Biv. Sic. PI. 1806-7. 



Uppermost leaves subcoriaceous. spatulate, opposite. (liv.uicat. 

 ing into a broad petiole as long as the blade. Ottawa. ( Milan.. U* 



Potamogeton pusillus polyphyllus Moron?. Coult. Bot. <;.i*. 5: 5 



'inS 



. 



which are thickened, hardened and closely invested 



Potamogeton pusillus Sturrockii A. Bennett in Hook. Stud. Fl. 

 A rare form with delicate bright green pellucid leaves,' .V l..n* . obtn- ,-r ,. 

 apex, less than i" wide, sometimes ^-nerved : fruit much smaller than i 



the apex, 



beaked. Eastern Massachusetts. Also in Europe. 



