Rhodora 
JOURNAL OF 
——. 
January, 1909. No. 121. 
Vol. 11. 
THE REPRESENTATIVES OF POTENTILLA ANSERINA IN 
EASTERN AMERICA. 
M. L. FERNALD. 
Boranists who have collected both.in northern New England and 
on our seacoast have long realized that the Silverweeds of these two 
regions are far from identical; but, owing to the confusion which has 
prevailed in regard to the identity of the many described variations of 
the species, the question has been left until the plants could be treated 
by a monographer. In November, 1908, two extensive monographs 
of Potentilla appeared, but when one turns to these two treatments with 
the hope of settling his long-standing problems the results are certainly 
disheartening. "Wolf, following the conservative practice of many 
generations, maintains Potentilla Anserina as a Potentilla of world- 
wide distribution, of which he recognizes eight leading varieties and 
numerous forms. Rydberg,’ on the other hand, treats the Silverweeds 
as a genus, Argentina, with eight North American species. It is, then, 
not surprising that the novice in this group finds himself perplexed to 
label with an approximation to truth the material in his herbarium. 
After spending some days in the study of the material in the Gray 
Herbarium and the Herbarium of the New England Botanical Club, 
the writer finds that, as the plants appear to him, they fall into two 
definite and recognizable groups. ‘These two pronounced tendencies, 
happily, are the same as those indicated by Wolf for the primary 
grouping of the varieties, and by Rydberg for the chief groups of his 
species; but, working independently, each author seems to have 
1 Theodor Wolf, Monographie der Gattung Potentilla, in Bibliotheca Botanica, xvi. 
pp. 1-714, Stuttgart (1908). 
2 Rydberg, Rosaceae (pars), in North American Flora, xxii. pt. 4, pp. 293-376, New 
York Botanical Garden (1908). 
