134 Rhodora [June 



recognize as P. filiform is, but for anything that appears in Boccone's 

 figure or description it might equally well he some form of the poly- 

 morphic P. pcctinafus. In just such cases as this we are authorized by 

 the International Rules for Botanical Nomenclature to cast aside the 

 name "when it becomes a permanent source of confusion." ' P. 

 setareum Schum. 1 is plainly the plant in question. In fact, Mr. 

 Bennett writes " I have seen a specimen named by him [Schumacher] 

 in Dr. Buchenau's herbarium." The name P. setaceum Schum. can- 

 not stand because it is antedated by a Linnean plant of the same name, 

 one which is maintained. The next name given to this plant was P. 

 filiform is Pers., based on Schumacher's plant, and this name seems 

 perfectly valid. Bennett when using the name P. filiformis credits 

 it to Nolte, but Nolte did not make this combination. He credits it 

 to Persoon, "S4. Potamogeton filiformis Persoon," and gives the Schu- 

 macher reference. 



P. filiformis Pers., var. orridentalis (Bobbins) Morong, Mem. Torr. 

 Bot. Club iii. no. 2, 51 (IS!):-}) (P. inferior Rydb.) from Ruby Lake, 

 Nevada, is a coarse sparsely branched plant, 5-6 dm. high, with a 

 few rather coarse leaves (0.5-0.7 nun. broad). Among the hundreds 

 of sheets of this group examined I have seen none to match the two 

 sheets at hand of the original collection of var. oeei<lentalis, conse- 

 quently it seems better to treat this plant (subsequently renamed 

 P. interior Rydb.) as a somewhat exceptional deep-water state of the 

 species. 



P. filiformis Pers., var. borealis (Raf.) n. comb. /'. horealis Raf., 

 Med. Repos. ii. '554 (1N0S). Resembling P. filiformis but differing 

 in the strongly marked tendency to have the spike short, with the 

 whorls approximate: leaves finely setaceous, 0.25-0.5 mm. broad; 

 mature spike 0.5 2.5 cm. long, the upper vcrticels mostly approximate, 

 the lower approximate or at most 7 mm. apart. Chiefly in calcareous 

 waters, Newfoundland to northern Maine, New York and Pennsyl- 

 vania, west to Alaska and south to Colorado; also in India, Tibet and 

 ( hina. 



NEWFOUNDLAND: border of Castle Pond, Tilt Cove, northern 

 shores of* Notre Dame Bay, Aug. 21, 1911, M. L. Ferntdd, K. M. U'ie- 

 gand & II. T. Darlington, no. 4,493 (H); shallow pools, wet runs and 

 boggy spots in limestone barrens, near sea-level, Ingornachoix Hay, 

 Aug. 4, 1910, M. L. Fernald, K. M. Wiegand & J. Kittredge Jr., no. 

 2,400 (H); pools on serpentine tableland, 550 m. altitude, northeast- 



1 Internal. Hull's Hot. [Somen., Vienuu, Art. 51, 4 (1905). 



2 Schumacher, Enurn. PI. Saellandiae i. 51 (181)1). 



