1920] Fernald,—Pyrola rotundifolia and P. americana 121 
PYROLA ROTUNDIFOLIA AND P. AMERICANA. 
M. L. FERNALD 
-. Wuen, in 1904, I pointed out! the distinctions between the north- 
ern Eurasian Pyrola rotundifolia L. and the Alleghenian P. americana 
Sweet, no material was available which clearly broke down the dis- 
tinctions between the two, and this fact was reinforced by the iso- 
lation of the two plants and the decidedly southern and dry habitat 
of P. americana, contrasted with the northerly and more varied 
habitat of P. rotundifolia. 
In 1904 a single collection was at hand which somewhat bridged 
the gap between the two plants. This material, from a sphagnum 
swamp at Manuel's, Newfoundland (Robinson & Schrenk), smaller 
in all details than the continental P. americana, was at that time sup- 
posed to be referable to P. asarifolia Michx., var. incarnata (Fisher) 
Fernald. Subsequent experience in Newfoundland, however, has 
shown that the plant of the Manuel's sphagnum swamp is generally 
distributed throughout the central and southeastern acid region of 
the island and that in every character it exactly connects Eurasian 
P. rotundifolia and Atlantic American P. americana. The Newfound- 
land plants have been studied with the greatest care at different in- 
tervals during a period of several years, always with the same result, 
namely: the Newfoundland plant seems inseparable from Eurasian 
material of P. rotundifolia, var. arenaria Mert. & Koch and this 
differs in no morphological character from the continental and more 
southern P. americana. The only differences are those of size, var. 
americana running larger in all its parts. The latter plant throughout 
most of its range, from Nova Scotia, Prince Edward Island, western 
Bonaventure and Rimouski Cos., Quebec to Frontenac Co., Ontario, 
South Dakota and Georgia, inhabits dry or sandy woods, but north- 
ward, at the northeastern limits of its range, for example, on the upper 
St. Francis in Maine, at Bic, in Rimouski Co., Quebec, and at Nou- 
velle in Bonaventure Co., Quebec, var. americana. is found only in 
wet, mossy, spruce woods or at the borders of sphagnum bogs. In 
this interchange of habitats P. rotundifolia, var. americana falls into 
the same class of oxylophytes as Cypripedium acaule Ait., Epigaea 
!'Ruopona, vi. 201 (1904). 
