1916] St. John, — Potamogeton, Section Coleophylli 131 



Rootstock coarse, 2-3 mm. thick: stem freely branching above; 

 2-4 branches at a node: principal sheaths swollen, 2-5 times thicker 

 than the stem, 2.5-5 cm. long, 2-5 mm. broad, with prominent veins 

 bending into the blade but not appearing in the entire very short (1 

 mm.) ligule; blade short, blunt, ribbon-like, 1-4.5 cm. long, 1-2 mm. 

 broad, the veins and cross veins forming a coarse rectangular pattern; 

 upper leaves filiform, blunt or more commonly retuse, 5-11 cm. long, 

 0.2-1 mm. broad; upper sheaths less swollen, bearing longer ligules: 

 peduncles short, 3 8 mm. long: spikes 1-6 cm. long, interrupted, with 

 numerous (5-12) whorls of flowers, which are equally spaced or the 

 lower more remote: fruit obliquely obovate, not prominently keeled, 

 3 mm. long, 2 mm. wide; the sessile stigma borne near the ventral 

 margin. — Deep waters from Labrador west to Saskatchewan and 

 Alberta and south to New York, Wisconsin, and North Dakota. 



Labrador: shallow sandy-bottomed pools, Blanc Sablon River, 

 Aug. 2, 1910, M. L. Fcmald & K. M. Wiegand, no. 2,403 (H). Que- 

 bec : above tide mark in Blanc Sablon River, Brest, Saguenay County, 

 Silly 31, 1915, Harold St. John (C). Ontario: Moose Factory, James 

 Bay, Julv 15, 1904, W. Spreadborough, (C no. 02,661); shallow water, 

 Misinaibi River, Aug. 1880, R, Bell, (C no. 3,013) New York: 

 in 8 feet of water, Lake Cayuga, July 16, 1916, Emmeline Moore. 

 Manitoba: Palliser's Brit. N. Am. Expl. Expedition, Lac Winnipeg, 

 26 Juin 1859, E. Bourgeau (H & Y). Saskatchewan: between 

 Cumberland House and Hudson Bay, Aug., Drummond (H, type); 

 and on the same sheet, Carleton House (H); Palliser's Brit. N. Am. 

 Expl. Expedition, 1858, E. Bourgeau (H & Y); Long Lake, July 6, 

 1879, Macoun, (C no. 4,176 & Y); in Cypress Lake, Cypress Hills, 

 June 29, 1895, Macoun, (C no. 10,470); in water, Buffalo Lake, Aug. 

 'A, 1888, ./. M. Macoun, (C no. 4,175). Wisconsin: University Bay, 

 Lake Mendota, Aug. 19, 1912, R. II. Denniston (H). North Dakota: 

 Turtle Mts., Aug. 20, 1891, Wright, no. 727 (R). Alberta: Vermil- 

 lion Lake, Banff, Rocky Mts., Aug. 13, 1891, Macoun, (C no. 4,374 in 

 part); Vermilion Lakes, 4,500 feet altitude, Banff, July 23, 1906, S. 

 Brown, no. 695 (A); in a lake, Milk River Ridge, July 20, 1895, 

 Macoun, (C no. 16,469). 



In 1854 P. vaginatus Turcz. 1 was described from a subsaline lake 

 near Selenginsk, south of Lake Baikal, Siberia. In the original 

 diagnosis the following characters are mentioned: sheaths loose, 

 flowers in interrupted whorls, fruit obliquely obovate, finely striate, 

 and leaves linear-setaceous, acute. Kihlman, 2 in recording P. vagi- 

 natus Turcz. from Europe for the first time, gives a careful description 

 of the type material and a critical discussion of the species. He 



1 Turcz., Bull. Soc. Natur. Moscou, xi. 102 (1838) (nomen solum), xxvii. 65 (1854); Flora 

 Baicalerisi-Daliuricu ii. 102 (1856). 



2 Osw. Kihlman, Meddel. af Societas pro Fauna et Flora Fennica, xiv. 111-115 (1887). 



