140 Rhodora [Avavsr 
Purshii and E. peregrina the difficulties surrounding this group have 
been removed. It is believed that they are in part ameliorated, but 
while E. peregrina and «E. Purshii appear to be very definite species 
units, each quite constant in its characters, the same cannot so cer- 
tainly be said of E. pilosa. In fact the amount of variation seen in the 
material grouped together under E. pilosa is so much more pronounced 
than in the two allied species that it is strongly suspected this is by 
no means a homogeneous series. E. Purshii has proved to be so 
satisfactorily separable, despite critical opinion to the contrary, that 
one is naturally inclined to a belief that this is a group still deserving 
careful study. 
ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA. 
A NEW POLYGONUM FROM SOUTHEASTERN MASSA- 
CHUSETTS. 
M. L. FERNALD. 
IN 1913, while exploring the ponds of Plymouth, Massachusetts, 
with Messrs. Francis W. Hunnewell and Bayard Long, the writer was 
much interested in a strictly indigenous annual Polygonum of the 
sandy pond-margins which was obviously related to the naturalized 
P. Persicaria L. but which had more slender and more richly colored 
spikes. Although it was obvious that this indigenous plant of south- 
eastern Massachusetts could not be exactly matched by P. Persicaria, 
no serious attempt was made to differentiate the two until further 
observations could be made. It is noteworthy, however, that in 
1915, Mr. C. A. Weatherby, collecting the plant of “sandy strand of a 
pond" on Cape Cod, should have labeled his material “ Pol lygonum 
Persicaria L.?” In 1918 the real opportunity to watch the plant 
came when the writer spent the summer on C ape Cod with side-trips 
into Plymouth. In this exploration he was accompanied most of the 
time by Mr. Long and the native Polygonum was found to be uni- 
versally distributed on the Cape, and everywhere a plant strictly 
of pond-margins. The ubiquitous weed, P. Persicaria, with its 
duller pink spikes, was naturally abundant near houses and about 
the farms, and the indigenous plant held its own peculiar differences 
