210 AMERICAN MIDLAND NATURALIST 
short cylindric” of the P. amphibium description. The only obvious 
conclusions the student is led to are that the manual makers have 
either not described what might be separate species by their 
proper distinguishing characters, or, that they did not know 
the plants they attempted to describe, and that this want of 
knowledge came from the fact that study in herbarium cf isolated 
separate aquatic and terrestrial phases not known to be physically 
connected, led to erroneous conclusions, and that separate names 
were applied to apparently separate plants that in reality were 
one. Further investigation on the part of the student reveals 
other facts. First of these is that there are amphibious persicarias 
which are easily distinguishable from others in not having in spring 
or at any other time, spreading borders to the ochreae whereas 
others always have them, and others again lose them at blooming 
time. Here plainly are three easily distinguishable groups pro- 
vided the complete set of seasonal phases are present. 
The student may notice too that some plants that have 
nearly the same shape of aquatic foliage never bloom except in 
different phases, or that their terrestrial phases growing under 
exactly similar conditions, often in the same place, are notably 
or unmistakeably different. The aquatic, for instance, of one of 
these never grows or blossoms except in deep water, whereas the 
other plant is normally terrestrial in flowering phases, never bloom- 
ing except out of water and on shoots with terrestrial foliage, 
and always clinging to the shore, and only producing a few aquatic 
leaves early in the season or when raising themselves from shallow 
water near shores. 
These observations could force the student only to the follow- 
ing conclusions. Either the manuals. because of their attempt 
to compromise are inconsistent, and we must go back to the 
Linnaean idea of one species of amphibious Persicaria, or we 
must accept a large number, with different standards of delimita- 
tion of the species than those found in these common manuals. 
Either view may be logical in itself and depends on the premises 
assumed as to the characters that distinguish species. The latter 
course is more reasonable if we weigh carefully or compare sedu- 
lously our idea of species as applied to other plants nowadays 
accepted by the manuals and floras. The via media, however, 
which consists of admitting one or two species besides P. amphibia, 
that is also P. Hartwrighttt and P. emersa, or either of these 
