204 AMERICAN MIDLAND NATURALIST 
norance on some things, or he decides to study plants from nature’s 
volume rather than from one of man’s making. 
Beside the taxonomic views of the amphibious smartweeds 
referred to, that of Linnaeus himself is not to be overlooked here. 
It was prevalent until the beginning of the nineteenth century 
without even being challenged in any detail. Linnaeus recc guized 
but one species which he called Polygonum amphibium. The reason 
I refer to his view is that as a result of field work for a number 
of years back, as also because of investigation cf some thousands 
of specimens, I have come to the conclusions, that, whatever 
premises have been taken up by our systematists as to the idea 
of delimitation of species of Water Persicarias, there is no logical 
position between that of Dr. Greene’s on the one hand and that of 
Linnaeus of the other extreme. In other words we may hold with 
the latter that there is but one species of Water Persicaria, or with 
the former that all the evidently different plants are distinct, 
but the via media of supposing that some are valid and others not, 
as held by our manualists, is positively untenable from a logical 
point of view. Either all must be accepted for they have absolutely 
the same reasons for acceptance or rejection, or none need be re- 
ceived. In the latter instance they will probably, if any show 
of consistency is used, be relegated to the status of “varieties”’ 
or ‘‘subspecies,”’ of P. amphibiwm Linn. 
In this connection I may say that in studying the plants, I 
have not confined myself to herbarium material which in the case 
of such variable plants as those in question, can be of little or no 
value whatever, not only in delimitation of the species, unless 
properly collected, but even in actually determining the identity 
of isolated specimens. In field study I have not confined my atten- 
tion to any one specimen which on careful examination could be 
more or less arbitrarily considered as an average type, but have 
whenever possible gathered all available varying forms of a specti- 
men to be found in a colony or locality. In this way I have at times 
collected as many as 50 to 100 samples of a specimen all of :which 
I was sure were not only one species, but which I was fairly sure 
came from one original rootstock. This was done that no variation 
of form or phase might possibly escape me of the transitions from 
aquatic, riparian, terrestrial, to xerophytic flowering or sterile 
plants. I have not, moreover, considered it sufficient to study 
any given plant at one time; for example, the flowering or fruiting 
