NOTES ON POTAMOaKTON 201 



P. ANGusTiFOLius Bercht. & Presl (P. ZUi Roth). Prof. Macoim 

 sends from Ontario, collected by Mr. W. Scott, a very interesting 

 form of what appears to be the above plant. It is a characteristic 

 specimen showing the lower leaves of liicens (or rather longifolins), 

 and the floating ones of heterophyllus. Dr. Morong gives "" leaves 

 (submerged) 2-6 in. long," but these are 12 in. and over, though 

 the floating leaves are only those of fine heterophyllus. 



P. PUsiLLus L. var. nov. capitatus. This was sent me by Prof. 

 Macoun from Sable Island, and I have also specimens from the 

 " Spallumsheen River, British Columbia, 10.7.1889, leg. J. M. 

 Macoun," which I had wrongly referred to my var. elongatus. The 

 present variety differs from the usual form of P. pusilhis by the 

 long and exactly linear leaves, tapering only at the extreme end, 

 the prominent medial nerve, the long and very slender peduncles 

 (the heads of flowers at a short distance looking as though they 

 are elevated above the plant without any peduncle), and the extra- 

 ordinary long hafts to the sepals (perianth-segments) ; these are as 

 long and often longer than the segment itself (the usual state being 

 something like a sixth of the segment) ; and the fruit-stems ap- 

 proach in character to those of my P. Aschersoiiii rather than the 

 usual form of pusilhis. 



P. PUSILLUS L. var. nov. pseudo-rutilus. Habit of P. rutilus 

 Wolfg., but with nearly the fruit of pusillus. Leaves linear attenuate, 

 rigid, spreading, central nerve prominent, laterals almost obsolete ; 

 stipules appressed to the stem, in the upper branches all as long as 

 the internodes ; apical propagating-buds abundant ; peduncles one 

 mch ; spikes dense-flowered. Differs from any form of pusilhis 

 known to me by its extreme rigidity, and the leaves all spreading 

 like a fan, by the substance of the leaf being nearly taken up by the 

 central nerve, by the strong and appressed stipules, and its likeness 

 to rutilus in habit. 



Lake Scugog, Ontario, Canada, 1897, W. Scott, ex Prof. Macoun • 

 Wolf Lake, Indiana, U.S.A., 1900, Bev. E. J. Hill. 



P. cRispus L. Since the publication of the North American 

 Naiadacem this species has been found in Canada. Morong over- 

 looked the fact that Pursh gives it from " Canada to Virginia " in 

 his Fl. Am. Sept. 120, 1814, marking it ''v v." as having seen a 

 hvmg specimen, and referring to Curtis's Fl. Lond. and Flora 

 Banica, t. 927. At a meeting of one of the American Botanical 

 Societies, Dr. Morong noted that it had been found in Arizona 

 (Bull. Torr. Bot. Club, 1886, 171) ; here he considered it had been 

 introduced by birds. The oldest dated American specimen I can 

 find in England is in Mr. Cosmo Melvill's herbarium, "Phila- 

 delphia, 1841-2, Gavin Watson & Kilvington." One from Delaware 

 in the British Museum Herbarium is probably older ; it was 

 collected by R. Eglesfeld Griffith, of Philadelphia, whose name is 

 not in Prof. Harshberger's volume on Philadelphia botanists. Prof. 

 Macoun now sends it from lakes at Niagara. 



(To be continued.) 



