1904] Fernald, — Pyrola rotundifolia 201 



appropriate name, though, unfortiiuatel}', he failed to point out the 

 characters upon which he based his conclusion. Sweet's Hortus 

 Britannicus was, as its secondary title explains, "a catalogue of 

 plants, indigenous, or cultivated in the gardens of Great Britain.'' 

 The species under each genus were numbered separately, then were 

 indicated the color, English name, geographic source, hardiness, dura- 

 tion, etc. The American plant, the ninth in Sweet's list of Pyrolas, 

 was thus entered : 



"9. americh.na. {ich.) American. N. America H. 2/. 



rotundifolia Ph. non Eng. bot.'" ^ 



The reference to Pyrola roliindifolia of Pursh, not of the English 

 l^otany, alone defines Sweet's species, for there can be no doubt that 

 Pursh's plant, "in dry stony or sandy woods: Canada to Carolina," ^ 

 was the common large-flowered plant of eastern America, which, 

 treated as a valid species, should bear the name P. amcriiaiia, Sweet. 



Briefly, the conclusions reached in this study are, that Pyrola 

 7-otuiidiffllia^ P. i^raiidiflora, and P. americana, are distinct though 

 closely related species, each occupying a well detined geographic 

 area and maintaining with essential constancy certain characters 

 notably in the size of the petals, and the size, proportions, and 

 forms of the anthers and filametits. 



The leading characters of the plants are : 



Pyrola rotuxdifoija, L. Sp. 396 (1753), as to European plant — 

 including var. arenaria. Koch. Syn. 478 (1837). Th?laia rotundifolia, 

 Alefeld, Linnaea, xxviii. 60 (1856). Plant varying in height from 

 15 to 30 (average 20) cm.: leaf-blade from 1.9 to 4.6 (average 3.3) 

 cm.: petals comparatively thin, white or slightly purple-tinged, 5.5 

 to 8 (average 6.5) mm. long: stamens 5 to 7.75 (average 6.27) mm. 

 long; the anthers 2 to 3 (average 2.5) mm. long, muticous or rarely 

 niucronulate at base, the cells narrowed above to short straightish 

 necks: style with a distinct ring or collar below the 5 protruding 

 lobes of the stigma.^ Greenland, Iceland, and Lapland, across north- 

 ern and central pAirope and western Asia and locally southward in 

 the mountains. 



P. AMERICANA, Sweet. Hort. Brit., ed. 2, 341 (1830). P. rotundi- 

 folia^ Am. autli., mostly. Plant 9 to 36 (average 25) cm. high : leaf- 

 blade 2 to 6.8 (average 4.4) cm. long : petals thick, cream-white, 

 rarely pink-tinged, 6.5 to 10.5 (average 8.4) mm. long: stamens 4.75 

 to 7 (average 6) mm. long; anthers 2.75 to 3.6 (average 3.2) mm. 



1 Sweet, Hort. Brit., ed. 2, 341 (1S30). 



2 Pursh, Fl. 299 (i8r4). 



