70 Rhodora [APRIL 
THE VARIATIONS OF POLYGONUM PENSYLVANICUM. 
M. L. FERNALD. 
THE common plant which is passing as Polygonum pensylvanicum ! 
L. through the eastern half of the United States is an upright plant, 
often very tall, with the lanceolate to lance-ovate acuminate leaves 
usually quite glabrous upon both surfaces or sometimes with a mere 
trace of strigose pubescence upon the midrib beneath. The plant 
is so definitely glabrous, not only on the stem but on the foliage (the 
only pubescence being the pronounced glandularity of the peduncles), 
that it is often characterized in our American manuals as having the 
foliage glabrous beneath. 
This plant with strictly or essentially glabrous foliage occurs gener- 
ally from New Brunswick to South Dakota and Colorado and south- 
ward to the Gulf States, very often with the habit of a weed. Along 
the Atlantic seaboard, however, from eastern Massachusetts to South 
Carolina and presumably southward, as well as on the coastal plain 
of the Gulf of Mexico and inland through the Mississippi basin to 
southwestern Ontario, much of the plant with the characteristic 
bright-pink large flowers and the glandular peduncles of Polygonum 
pensylvanicum has the leaves very definitely strigose beneath and 
sometimes above, and frequently the upper ocreae are bristly-ciliate, 
thus departing conspicuously from the glabrous extreme which is 
more generally known as Polygonum pensylvanicum; and often, but 
by no means always, the leaves of the coastal plain plant are narrower 
than in the more widely dispersed glabrous-leaved plant. On the 
islands of southern New England, Nantucket and Block Island, 
another plant with the large achenes, rose-colored flowers and glandu- 
lar peduncles of Polygonum pensylvanicum, differs very markedly 
from the commoner tendencies of the species in its habit, foliage and 
nearly suppressed peduncles. This extreme plant, which is said by 
1 The specific name pensylvanicum was consistently so written by Linnaeus and by his con- 
temporaries, but in most modern works it has been made to agree with modern geographic 
usage and written “‘pennsylvanicum,”’ apparently under the impression that an orthographic 
error is thus being corrected. Maps of the 18th century generally show the spelling Pensyl- 
vania so that it appears that Linnaeus, Lamarck and others who wrote the specific name with a 
single n in the first syllable were not committing an orthographic error but were following the 
authorized spelling of their day. 
