The American Midland Naturalist 
PUBLISHED BI-MONTHLY BY THE UNIVERSITY 
OF NOTRE DAME, NOTRE DAME, INDIANA. 
VOL. Il. JANUARY, 1911. NO. 1# 
OUR AMPHIBIOUS PERSICARIAS. 
J. A. NIEUWLAND. 
There seems to be a rather widespread opinion among plant 
students and even botanists of note that Persicaria ‘amphibia 
Linn., the Water Persicaria, is an aquatic plant, and Persicaria 
Hartwrightw A. Gray, is a terrestrial variety of it brought about 
by the fact that the aquatic plant was somehow made to take 
up a terrestrial or xerophytic habit. This idea seems to have 
gained strong hold particularly since the new Gray’s Manual of 
Fernald and Robinson entirely suppressed the latter species 
. reducing it to the rank of a mere variety. No one since the publica- 
tion of the species by Dr. Gray seriously questioned its right to 
specific standing. Even when this rank was recognized the former 
was invariably described or illustrated as an aquatic and the 
latter as a land plant, because P. Hartwrighttt was only known as 
-a rough pubescent terrestrial and because P. amphibia was by 
American writers at least, not described or illustrated as any- 
thing, but a water-plant. Most of the information for students 
regarding it was gleaned from manuals. Britton and Brown’s 
Illustrated Flora of N. America, and Small’s Monograph of N. 
Am. Species of Polygonum show only aquatic phases of P 
amphibia and all the manuals describe it as a submerged water 
plant with floating smooth leaves, and a rose to purple short 
spike of flowers. Though the specimens of the European plant that 
have come under my observation are not many, P. amphibia 
of the old world, I have nearly always seen in herbaria as a 
rough leaved terrestrial plant without the least indication of 
aquatic habit. It would seem strange then that this rough leaved 
plant hardly appears to be mentioned in the manuals during the 
* January 15, 1911.—Pages 1 to 28. 
