PIPER — FLOEA OF THE STATE OF WASHINGTON. 97 



Floating leaves none. 



Leaves all oblong or lanceolate. « 



Base of leaves clasping; apex acuminate 7. P. perfoliatus. 



Base of leaves not clasping; apex not acuminate. 



Leaves obtuse, cucullate, sessile 8. P. -praelongus. 



Leaves acute, short-petioled 9. P. lucens. 



Leaves all narrowly linear. 



Stipules adnate to the sheathing base of the leaf. 



Leaves setaceous, 1 to 5-nerved 13. P. pedinatus. 



Leaves linear-lanceolate, many-nerved 14. P. robbinsii. 



Stipules free. 



Leaves tape-like; spike cylindric; fruit large 10. P. zosteraefolius. 



Leaves not tape-like; spike not cylindric; fruit small. 



Spike capitate; peduncles very short 11. P. calif omicus. 



Spike interrupted; peduncles long 12. P. pusillus. 



1. Potamogeton natans L. Sp. PI. 1: 126. 1753. 

 Type locality: European. 



Range: North America. Europe. Asia. 



Specimens examined: Cascade Mountains, 49°, Lyall in 1859; Oyhut, Lamh 1259; 

 Tacoma, Fleit 135; Falcon Valley, Suksdorf, July 17, 1886; Pend Oreille River, Lyall in 

 1861. 



2. Potamogeton nuttallii Cham. & Schlecht. Linnaea 2: 226. t. G.f. 25. 1827. 

 Potamogeton clayionii Tuck. Am. Journ. Sci. 14: 38. 1843. 



Type locality: None given. 



Range: Washington and Oregon to Nova Scotia and South Carolina. 



Specimens examined: Montesano, //fiZ/er4072; llwaco, ffemZcrsonin 1886; Lake Wash- 

 ington, Piper, September, 1892; Mount Constitution, Henderson 2477; Spokane County, 

 Henderson 2476; Waitsburg, Z/orri^r R 16. 



3. Potamogeton amplifolius Tuck. Am. Journ. Sci. IL 6: 225. 1848. 

 Type locality: Cambridge, Massachusetts. 



Range: British Columbia to Ontario, south to Washington and Nebraska. 

 Specimens examined: Coupeville, Gardner 421; Pullman, Henderson 2474; Kalispel 

 Lake, Kreager 441; Whatcom County, Suksdorf, August 1, 1890. 



4. Potamogeton alpinus Balbis, Mem. Acad. Turin 7: 323. 1803. 

 Potamogeton rufescens Schrad.; Cham. Ad. Fl. Ber. 5. 1815. 



Type locality: European. 



Range: British Columbia to Labrador, south to California and New Jersey. 

 Specimens examined: Mount Adams, Suksdorf, September, 1879; Trout Creek, Suks- 

 dorf 2\12. 



6. Potamogeton heterophyllus Schreb. Spicileg. Fl. Lips. 21. 1771. 



Type locality: "In stagno ad Lindenthal," Germany. 



Range: Throughout most of North America. Europe. 



Specimens examined: Lake Chelan, Lake <fc Hull 614; Okanogan River, Watson 396; 

 Tumwater Canyon, Sandberg cfe Leiberg 524; Falcon Valley, Suksdorf, August, 1885. 



• 

 6. Potamogeton lonchites Tuck. Am. Journ. Sci. 11. 6:226. 1848. 



Type locality: "Common in New England and extending southward to Virginia." 

 Range: Washington to New Brunswick, south to California and Florida. 

 Specimens examined: Clallam County, Elmer 2798; Silver Lake, Henderson 2475; 

 Okanogan River, Watson 398; Pend Oreille River, Lyall in 1861; Whitman County, Hen- 

 derson 2473; Union Flat, Piper, August 4, 1899, without locality, Vasey in 1889. 

 29418—06 m 7 



