GENUS i. 



POXDWEED FAMILY. 



23. Potamogeton Friesii Ruprecht. Fries' 

 Pondweed. Fig. 196. 



Potamogeton cotnpressus T. E. Smith, EngL Bot. 3 : 



pi. 418. 1794. Not L. 1753. 

 Potamogeton pusillus var. major Fries, Xovit. Ed. 2, 



48. 1828. 

 Potamogeton Friesii Ruprecht, Beitr. Pfl. Russ. Reichs, 



4: 43. 1845. 

 Potamogeton major Morong. Mem. Torr. Club. 3 : Part 



-. 41. 1893. Xot P. pusillus var. major M. Si K. 1823. 



Stems compressed. 2-4 long, branching. Lea- - 

 \\'-2\' long, about i" wide, acute, obtuse or cuspi- 

 date at the apex, mostly 5-nerved. rarv'.y 7-::crved, 

 2-glandular at the base, the glands small; stip 

 white, hyaline, finely nerved, obtuse or acute. 6"-i2" 

 long; peduncles i'-i*' long, often thicker than the 

 stem and sometimes thickening upward : spikes, when 

 developed, interrupted ; fruit quite similar to that of 

 P. pusillus. but with a recurved style, use 

 shallow pit on the sides, and with the apex of the 

 embryo pointing toward the basal end. 



In still water, Xew Brunswick to Xew York, west to 

 Xorth Dakota and Iowa. Also in Europe, Propagating buds occasional. July- Aug. 



24. Potamogeton rutilus \Volfg. Slender 

 Pondweed. Fig. 197. 



Pctamogeto- Lfg R. i 5. I ' . : 362. 1827. 



Stems very slender. 5 _ _ g, coi 

 or nearly so. Leaves i'-ii' long. 

 or acur - ::. "early e- : ... invo- 



lute, th-; - prominent ber 2-glai I ' r 



at base and bright green: stip - :e. 6"-io" long, 

 often longer than the inrernodes and hiding the t - 

 of the leaves above, persisten - and 



fibrous with age; peduncles 6"-i8" long: spikes 3"-?" 

 long, usually dense, bv.: - temipl Eruil 



obi: :" long an I ob- 



scurely keeled or the back showing only _ 

 grooves : apex of the drtr - short 



facia! nearly straight recurved style ; embryo c: 

 not complete, the apex p - 



the base. 



Anticosti : - ga - " 



south to Xew Yor so in Europe. Propagi- _ 



buds usua' . ::ng. 



25. Potamogeton Vaseyi Robbins. \ asey's 

 Pondweed. Fig. 198. 



Potamogeton I'c.scvi Robbins in A. Gray. Man. Ed. 5. 



485. 1867. 

 Potamogeton :' var. latifolius Morong. Mem. Torr. 



Club. 3 : Part 2. 44. iE 



Stems filiform, widely branching below, and with 

 many short lateral branches above, i 3 -!;" long, the 

 emersed fertile forms in shallow water, and the more 

 common sterile submerged forms in water from 6~-^' 

 in depth. Floating leaves on the : -:ems only, 



coriaceous, in 1-4 opposite pairs, oval oblong or 

 obovate, 4"-5" long, 2 "-3" wide, with 5-9 nerves 

 deeply impressed beneath, tapering at the base into 

 petioles 3"~4" long : submerged leaves capillary, i '- : '_' 

 long: stipules white, de'.icate. irany-nerved. acul 

 obtuse, J "-3" long; peduncles 3 "-6" long, thicker _ 

 in fruit: spikes 2 "-3" long. 2-6-f ruited : fruit round- 

 ish-obovoid. about i" long and nearly as thick. 

 3-keeled, the middle keel rounded, tipped with a 

 straight or recurved style. 



Quebec to \\~isconsin, south to southern Xew York. 

 The plant is furnished with propagating buds. July- Aug. 



