28 LEAFLETS. 
about 3, lanceolate, 14 inches long on glandular-scabrous pedun- 
cles: bracts broadly ovate, acute, glabrous. 
In the northern Sierra Nevada, California, Silver Lake, 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 Poly- 
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. Riparian. 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 2 inches or more, of 
lanceolate outline and about 17 inches long, with commonly an 
isolated bract an inch below the spike subtending a glomerule of 
3 or 4 flowers: bracts ovate, barely acutish: achenes round- 
ovate, black, highly polished yet very minutely shallow-pitted 
Known to me only in a fine U. S. Herb. sheet collected at 
Galt, Ontario, 1? Aug., 1899, by L. 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 | 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. MEsocHORA. 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 
14 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-peduncled, 
cylindric, 1 to 14 inches long. 
Riparian state. Stem stouter, the 3 or 4-inch-long internodes 
somewhat fistulons: leaf-blades broadly lanceolate, very acute, 
