PONDWEED FAMILY. 



$7 



3. Potamogeton amplifolius Tuckenn. 



I\>ta>nntfftt>H tnnf>lifi>lins Tuckerm. Am. Journ. Sci 



(I I.) 6: 225. 1848. 



Stems long, simple or occasionally branched. 

 Floating leaves oval or ovate, abruptly pointed at 

 the apex, rounded at the base, 2 / ~4 / long, \^ f -2 f 

 wide, many-nerved ; petioles $'-5' long ; sub- 

 merged leaves mostly petioled, large, the upper- 

 most often elliptic or oval, 3'-6' long, i / -2 / J^ / 

 wide, the lowest lanceolate, often 8' long, with 

 about 25 nerves, often with the sides of the blade 

 closed and assuming a falcate shape ; stipules 

 tapering to a long sharp point, sometimes 4' 

 long ; peduncles thickened upward, 2 / -8 / long ; 

 spikes cylindric, i / -2 / long; fruit 2 // -2^ // long, 

 i '4 " thick, turgid, the pericarp hard, obliquely 

 obovoid, 3-keeled ; face more or less angled ; 

 style subapical ; embryo slightly incurved. 



In lakes, Ontario to British Columbia, south to 

 Connecticut, Kentucky and Nebraska. July-Sept. 



4. Potamogeton pulcher Tuckerm. 



Large-leaved Pondweed i 



5. Potamogeton Nuttallii Cham. & Sch. 



Potamogeton Xiiftallii Cham. & Sch. Ijnnaea, 2: 



226. pi. 6./. 25. 1827. 

 Potamogeton Claytonii Tuckerm. Am. Jouni. 



Sci. 45: 38. 1843. 



Steins slender, compressed, mostly simple, 

 i-6 long. Floating leaves opposite, elliptic, 

 sometimes obovate, obtuse at the apex, short- 

 petioled, \Yz f -^/i' long, 4"-! 2" wide, many- 

 nerved ; submerged leaves linear, 2-ranked, 2 / -7 / - 

 long, i // -3 // wide, 5-nerved, the 2 outer nerves 

 nearly marginal, the space between the 2 inner 

 and the midrib coarsely reticulated ; stipules 

 obtuse, hyaline, not keeled; peduncles I'-s' 

 long; spikes YZ'-I' long; fruit round-obovoid 

 ! #//_ 2 // long, \"-\W thick, 3-keeled, the sides 

 flat and indistinctly impressed ; style short, 

 apical ; embryo coiled one and one-third times. 



In ponds and streams. Nova Scotia to Pennsyl- 

 vania and South Carolina. June-Aug. 



Spotted Pondweed. (Fig. : 



/;</<(// />///<//,/ Tuckerm Am J..urn. Sci. 



45: 38. i 



Stems simple, terete, black-spotted, l-2 

 long. Floating leaves usually massed at the 

 top on short lateral branches, alternate, ovate 

 or round-ovate, subcordate, 2'-454' lonx 

 3#' wide, many-nerved ; peduncles about as 

 thick as the stem, 2' -4' long, spotted ; nib- 

 merged leaves of 2 kinds, the uppermost pellu- 

 cid, lanceolate, long-acuminate, undulate, 3'-4J' 

 long, 6"-iS" wide, tapering at the base into a 

 short petiole, io-2o-nerved ; the lowest much 

 thicker, opaque, spatulate, oblong or ovate, on 

 petioles X'~4' l n g '< stipules obtuse or acumi- 

 nate, 2-carinate; fruit 2"-2X"long, i 3 " thick, 

 turgid, tapering into a stout apical style, the 

 back sharply 3-keeled , face angled near the 

 middle, with a sinus below ; embryo coiled. 



In ponds and pools, Maine to Gcotfia and Mis- 

 souri. July. 



Xuttall's Pondweed. 1 



. 



