214 AMERICAN MIDLAND NATURALIST 
in others, we can hope for nothing but hopeless confusion and 
ignorance. The examples quoted have, I think, sufficiently shown 
this. The authors who will not admit the system must perforce 
logically go back to the Linnaean one species, P. amphibium, 
for on the basis of classification as now obtains in the manuals, 
P. emersa is as untenable as P. Hartwrightw. Admitting these 
two, we must also logically admit Dr. Greene’s species. 
Moreover admitting these two plants as separate species, 
and. logically also the others, one is also as logically led to the 
conclusion that there is no typical P. amphibia in America. The 
terrestrial phase of this has been many times described by European 
authors and lately again by Massart.* The only plants that could 
be mistaken for it are P. mesochora forms, and specimens of P. 
fluitans. The former has spreading herbaceous borders to its 
ochrea in the terrestrial phase, as have niany others such as P. Hart- 
wrightit, and P.ammophila which in aquatic form are somewhat like 
the European plant. P. fluitans has no known terrestrial form. 
P.amphibia of Europe never has these spreading margins in any 
phase whatever. P. emersa in its aquatic phase may be considered 
like P.amphibia, as I have pointed out, but to say that they are 
the same is equal to suppressing one of them. Moreover, there is 
no narrow-leaved terrestrial phase growing in America that suf- 
ficiently resembles that of the P. amphibia in Europe, that could 
possibly serve as a terrestrial phase to prove the existence of the 
real aquatic here. In other words as there is in America no terres- 
trial phase like that of the European P. amphibia, therefore, if the 
the latter exists here it exists without a corresponding terrestrial, 
none being like it here, and this fact alone renders its presence here, 
at least highly improbable. The absence of a terrestrial presup- 
poses the absence of the aquatic, and the aquatics we have are 
phases of one of the other Persicarias whose terrestrial phases 
differ from any European terrestrial plant. 
As few if any collectors in the past, or apparently at present, 
gather all the different variations or phases of these plants, or 
make any pretence to establish the relationship or identity of 
aquatic and terrestrial specimens from any given lccality, the 
determination is a difficult matter and sometimes quite impossible. 
Such ignorance of other plants would be considered intolerable 
* Massart, J. C. L’Accommodation Individuelle Chez Polygonum 
amphibium Bull, Jard. Bot. Vol. I Fase. 2, 1902. ; 
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