206 Canadian Record of Science. 



tance of three-fourths of an inch or less above the angle of 

 branching, a node with a leaf and ocrea, thus making an 

 internode several times shortor than normal length." 



Yar. strigosum, Small. 

 In ditches at Gatineau Point near Hull, Que. {John 

 Macoun.) In water near St. Patrick's Bridge, Ottawa, Ont. 

 (Jas. M. Macoun, Herb. No. 1,503.) 



(5.) P. Hydropiper, L. 

 From New Brunswick to Pacific Coast. 



(6.) P. punctatum, Ell. 



P. acre, Macoun, Cat. Can. Plants, Yol. I., p. 411. 



Not rare in Eastern Canada. Agassiz, B.C., and Kam- 

 loops, B.C. (John Macoun.) Not before recorded west of 

 Ontario. 



(7.) P. Pennsylvanicum, L. 

 Common from Nova Scotia to Western Ontario. 



(8.) P. LAPATHIFOLUIM, L. 



Common from the Atlantic to the Pacific. Prof. Small 

 thinks this species has been introduced wherever found. 

 While this may be so in most cases, we have specimens 

 from remote regions that are without doubt indigenous. 



Yar. incanum, Koch. 

 From Ontario to the Pacific. 



(9.) P. amphibium, L. 



Tadousac, Que. (Northrop.) Wingham, Ont. (J. A. 

 Morton.) Hastings Co., Ont.; Long Portage, Nipigon 

 River, Ont. ; Tail Creek, N.W.T. ; near Victoria, Vancouver 

 Island. (John Macoun.) Near Pincher Creek, Alberta. 

 (Dr. G. M. Dawson.) 



(10.) P. emersum, (Michx.) Britt. 



Most of the references under P. Muhlenbergii, Macoun, 

 Cat. Can. Plants, Yol. I., p. 410, and Yol. II., p. 353, go 

 here. Our herbarium specimens are from Wingham, Ont. 



