OUR AMPHIBIOUS PERSICARIAS 245 
as riparian in the sense I have used the word under the descrip- 
tion of P. mesochora or P. rigidula where for want of anything 
subaquatic in nature, I was forced to designate for these, a riparian 
plant, that is glabrous or perfectly aquatic below, and quite 
terrestrial above. P. ammophila I have not found to bloom as I 
have said, in any phase that did not have at least some terrestrial 
foliage above, though P. nebrascensis approached this aquatic 
habit more. On the basis of these facts I was forced to consider 
P. canadensis and P. nebrascensis and especially P. canadensis 
and P. mesochora as specifically distinct though their aquatic 
foliage to the superficial examiner appears indistinguishable in 
many cases. 
Dr. Greene* seems to suspect that P. canadensis “may possi- 
bly some day be shown to be the riparian state” of P. fluitans. 
I fear that P. ammophila may be yet shown to be the terrestrial 
phase of P. canadensis. There is more evidence in my specimens 
for this suspicion than for Dr. Greene’s. As, however, of all the 
hundreds of specimens I have collected or examined I have found 
no blooming strictly aquatic form of P. ammophila, | must refrain 
from drawing the conclusion, though the foliage of sterile aquatic 
of the latter can not be distinguished from that of P. canadensis 
or even P. fluitans when perfectly aquatic in nature. Field 
botanists may yet find plants of P. ammophila in which strictly 
aquatic and riparian and terrestrial forms connected on one shoot. 
Such a discovery may lead therefore to the recognition of but 
one of the three, 7. e., P. fluitans Eaton, the others to be only 
to be considered as phases of this the oldest name of them all. 
The following phases of hitherto known plants have been 
described by me in the preceding discussions on amphibious 
smartweeds. Some of these have been described in the preceding 
article. The types of all phases are in my herbarium except No. 7 
which is in the U. S. National Herbarium at Washington. 
1. Persicaria tanaophylla Nwd. Aquatic, subriparian and 
terrestrial phases. 
2. Persicaria mesochora var. areniwcola Nwd. Aquatic, and 
terrestrial phases. 
eh Persicavia mesochora Greene. ‘Terrestrial and riparian 
phases, also the early summer sterile terrestrial. 
* E.L. Greene Leaflets, Vol. I., p. 28. 
