206 Rhodora *(NovEMBER 
Boott, Aug. 23, 1853. "In a springy bog at Sluice Pond, Lynn, 1880” 
(E. Faxon, according to Robinson, Fl. Essex Co. 104. 1880); Ash- 
land (T. Morong, according to Dame & Collins, Fl. Middlesex Co. 
99. 1888). 
POTAMOGETON. 
Р. americanus C. & S. Running water, occasionally in ponds; 
Hyde Park, Natick, ‘Topsfield, Winchester, Mystic Pond. 
P. amplifolius 'l'uckerm. Ponds and rivers, frequent in northern 
half of district, also occurring in Canton. 
P. angustifolius Berchtold & Presl. Fresh Pond, Cambridge, 
(J. W. Robbins, Oct. 2, 1851; Wm. Boott, Sept. 5, 1853; collected 
by other botanists down to 1886); Mystic Pond (Wm. Boott, Aug. 26, 
); Pleasant Pond, Wenham (various collectors between 1875 and 
1884). First two stations probably extinct. 
P. bupleuroides Fernald. Fresh and brackish ponds; Cambridge, 
Lynn, Natick, Wakefield, Wellesley, Wenham, Mystie Pond. 
P. crispus L. Pools and ditches among the clay-pits іп Cam- 
bridge, abundant; also in Spy Pond, Arlington. 
P. dimorphus Raf. Ponds and streams, common north and west, 
but no reports south of Canton. 
P. epihydrus Raf. Ponds and streams; many records from all 
parts of the district. 
P. foliosus Raf. Still waters, from scattered stations in eastern 
half of district. 
P. gemmiparus Robbins. Rivers and ponds. Charles River at 
Dedham and South Natick; Neponset River at Dedham; Fresh Pond, 
Cambridge; Wenham Pond, Wenham; Mystic Pond (E. Tuckerman, 
according to Dame & Collins, Fl. Middlesex Co. 101. 1888). 
P. heterophyllus Schreb. Ponds and streams; numerous stations 
in northern half, and as far south as Canton. 
P. heterophyllus Schreb., forma graminifolius (Fries) Morong. 
Ponds, Stoneham, Cambridge, Wellesley, Natick, Ashland. 
P. heterophyllus Schreb., forma maximus Morong. Deep running 
water, Charles River, Natick (T. Morong, July 14, 1879 and Sept 5, 
1882); Charles River, Dedham (E. & C. E. Faxon, Aug. 2, 1880). 
P. heterophyllus Schreb., forma myriophyllus (Robbins) Morong. 
Ponds, from six scattered stations in north and west portion. 
