OUR AMPHIBIOUS PERSICARIAS 209 
leaved long-spiked congener, then, he is at least more logical 
than the writers of any of the manuals. I think, however, that 
there will be few taxonomists who will agree to this, so strongly 
has the specific standing of P. emersa obtained a hold. On the 
basis of suppressing all the amphibious persicarias but P. amphibia, 
the author ought to be consistent, suppress other specific ter- 
minations which are used in the work and have as little or less 
reason for recognition. 
In order to show how one would fare in the study of the 
amphibious persicarias with the help of the manuals we may 
suppose for example that a student taking either the New York 
or the New England manuals to determine the plants already refer- 
red to, viz: the one found at Luray, Va., the other at the Notre 
Dame Lakes. In regard to the former with the aid of both or 
either Britton’s or the new Gray’s manual, the student would 
find that the former is a-plant that the books call P. amphibium 
Linn., when floating in water, whereas branches on the same 
shoot higher up on the shore are typical P. Muhlenbergu Wats., or 
P. emersum Michx. When the student finds what the manuals 
call two separate species, on the same rootstock, to his mind comes 
the query: ‘“ How can one end of the plant be called one of these 
species and the other end an equally well recognized species?”’ 
Let us suppose, moreover, that the same student later finds in 
the Middle West a plant, which in early summer or spring, when 
not yet blooming, has the spreading herbaceous ochrea margins 
of what Gray’s New Manual calls P. amphibium Linn. var. Hart- 
wright (A. Gray) Bissel, or which Britton’s manual calls P. 
Hartwright A. Gray. The same student watches the plants care- 
fully until late in summer and autumn, and finds that the spreading 
herbaceous margins gradually disappear so completely, that at 
flowering time one part of the plant growing on land near the water 
resembles narrow leaved forms of typical P. emersuwm according 
to the books, as it grows along the Potomac River for example, 
whereas another part of this same western plant taking to water 
becomes a floating glabrous slimy aquatic that finds no descrip- 
tion in the manuals save that for P. amphibium Linn. These 
water shoots have no longer “‘/eaves lanceolate to ovate acuminate, 
and peduncle hispid often glandular.”’ on which one of these manuals 
puts so much stress, but now in water have “obtuse or acutish 
leaves’’ and “peduncles glabrous, spike terminal, dense ovoid or 
