192 METCALF: NOTES ON NORTH DAKOTA PLANTS 



Metigoshe and St. John, Turtle Mountains. Also observed there (No. 

 544, Sept. 2 1, 191 7) and in Roland Twp.*S. 16, S. 4-9, and Pelican Lakes, 

 Bottineau Co.; Upsilon (No. 459, Sept. 7, 191 7, D. C. Mabbott) 

 Carpenter, Crowell and Jarves Lakes, Rolette Co. and Foothill Twp. 

 S. 20-39, Burke Co. 



Potamogeton perfoliatus Linnaeus. Abundant in the northern coun- 

 ties of the state, less abundant in the southern tier of counties ; prefers 

 shallow, slightly alkaline or fresh water. This species was represented 

 by two forms, one of which was characterized by sessile, lanceolate to 

 narrow ovate-lanceolate leaves with acuminate apex agreeing with P. 

 Richardsonii (Bennet) Rydberg (P. perfoliatus Richardsonii Bennett) ; 

 the other with clasping perfoliate, ovate-lanceolate to ovate leaves with 

 acute apex representing P. perfoliatus L. Every possible intermediate 

 intergradation between these two forms was found, suggesting that 

 all should be treated as belonging to a single species. 



Potamogeton praelongus Wulfen. Not previously reported from the 

 state but comes within general range commonly given. Found spar- 

 ingly in Pelican Lake, Bottineau Co. in the Turtle Mountains (No. 546, 

 Sept. 24, 1 91 7). 



Potamogeton zosterifolius Schumacher. Rather rare, only found in 

 King Slough, Burleigh Co. (No. 344, Aug. 24, 191 7); Painted Woods 

 Lake, McLean Co. (No. 440, Sept. 3, 1917) and Jim Lake, Stutsman Co. 

 (No. 315a, Aug. 14, 1917, D. C. Mabbott). Bergman reports this only 

 from St. John and Lake Ibsen (extinct). 



Ruppia maritima Linnaeus. Abundant throughout the state in 

 slightly alkaline-saline or saline water. A few plants were noted that 

 approach very closely to R. occidentalis Watson of Britton and Brown's 

 Manual (sheaths \^li'-2' and achenes iV2"-2"); others less vigorous 

 (sheaths 3 "-4" and achenes i") resemble R. maritima; another 

 approaches var. longipes Hagstrom and one, very much stunted seems 

 identical with R. maritima var. rostrata Agardh. (Rhodora, Vol. 

 16, No. 167, pp. 1 19-127). However, the large forms that approached 

 R. occidentalis were always found in the least alkaline lakes under the 

 most favorable conditions (Brush Lake, McLean Co., No. 457, Sept. 

 5, 19 1 7, total concentration of salts 1 103 parts per million and Thompson 

 Lake, Burke Co., No. 564, Oct. 2, 1917, no fruit); forms representing 

 typical R. maritima in somewhat similar or slightly more alkaline lakes 

 (Isabel Lake, Kidder Co., No. 209, Aug. 6, 1917, total concentration of 

 salts 2512 parts per million; Long Lake, Underwood, McLean Co., No. 

 405, Sept. I, 1 91 7, total concentration of salts 457 parts per million; 

 Salt Lake, Dawson, Kidder Co., No. 209, Aug. 6, 191 7, total concentra- 

 tion of salts 3906 parts per million), while on the other hand the less 

 vigorous forms, var. longipes Hagstrom were found under adverse con- 

 ditions in the strongly alkaline-saline lakes (Moon Lake, Barnes Co., 

 No. 220, Aug. 3, 191 7, D. C. Mabbott, total concentration of salts 

 5,779 parts per million), and the most stunted of all R. maritima 

 var. rostrata was found in the very salt Kellys vSlough, Grand Forks 



* Township, Section 16, Section 4-9, etc. 



