about 3, lanceolate, li inches long on glandular-scabrotfB J>edttn- 

 eles : bracts broadly ovate, acute, glabrous. 



In the northern Sierra Nevada, California, Silver Late, Las- 

 sen Co., 30 July, 1894, Baker and Nutting; both states at the 

 same place and same date, and extremly dissimilar as to outline 

 of leaves and characters of the spikes ; yet both were distributed 

 under my direction indiscriminately under the name of I'ofy- 

 gonum amphibium. An excellent sheet of the riparian state Was 

 communicated to the U. S. Herb, and is the type of that part of 

 the above diagnosis. 



P. CANADENSIS. Eiparian. The rather hard and wiry pros- 

 trate stems slender, with internodes of an inch or more : leaves 

 lance-elliptic, 2 or 3 inches long on short not slender petioles, 

 green and glabrous, on the petioles and basal part of some of the 

 reduced floral ones scabrous-strigulose : spikes one or two, borne 

 well above the foliage on a peduncle of 3 inches or more, of 

 lanceolate outline and about If inches long, with commonly an 

 isolated bract an inch below the spike subtending a glomerule of 

 3 or 4 flowers : bracts ovate, barely acutish : aehenes round- 

 ovate, black, highly polished yet very minutely shallow-pitted. 



Known to me only in a fine U. S. Herb, sheet collected at 

 Gait, Ontario, 17 Aug., 1899, byL. M. Umbach, who reports it 

 an inhabitant of small lakes. The stem is partly submersed, 

 no doubt, but all the foliage present at flowering time, as well as 

 the peculiar spikes and peduncles, are wholly aerial and not 

 floating ; whence I infer the specimens to be properly riparian. 

 The habitat is entirely within the range of the aquatic P.fluitans 

 and the plant may possibly some day be shown to be the riparian 

 state of that ; but I think not. 



P. MESOCHOBA. Aquatic state. Larger and stouter than any 

 of the foregoing ; petioles as long but not slender ; leaf -blades 

 of another hue, being light-green, commonly 5 inches long and 

 li to 2 inches breadth, ovate to elliptic-lanceolate according as 

 the base is broad and subcordate or somewhat tapering, glabrous 

 more or less puncticulate : spike solitary, rather long-pedunclfed 

 cylindric, 1 to IJ inches long. 



Riparian state. Stem stouter, the 3 or 4-inch-long internodes 

 somewhat fistulous : leaf -blades broadly lanceolate, very acute 



