JOHNSON: A REVISION OF THE SECTION BORAPHILA 41 



Geographically the species are almost wholly confined to the United 

 States. There are two well-marked distributional belts practically within 

 the same latitudinal range, one eastern, the other western. The eastern belt 

 runs westward from New Hampshire and Massachusetts into Minnesota, 

 Iowa, and Missouri, occupying practically all the area between the Great 

 Lakes and the Ohio River, with a narrow strip in Canada along Lake Erie 

 and Lake Ontario. The belt is dominated by 5. pennsylvanica. At the 

 extremities of the range certain peculiar types have been differentiated, to 

 which may be added certain apparently distinct types from the center of 

 the range. The exact status of these types can not be established at present. 

 An interesting feature in this connection is the remarkable similarity be- 

 tween certain specimens from the Yellowstone National Park region and a 

 specimen from the Winnebago Valley in Minnesota. 



The western distributional belt lies in the form of a deep inverted 

 crescent, the points of which rest on the same parallel of latitude, on the 

 southern boundary of Colorado, in the Rocl<y Mountains, and a short dis- 

 tance north of Tulare Lake, California, respectively. The arms of the 

 crescent follow the courses of the mountains northward, with the main 

 body occupying the watershed of the Clark's Fork, the Clearwater, and the 

 Snake rivers, and the lower course of the Columbia. A small, apparently 

 detached belt, occupied by a single species, surrounds the shores of Puget 

 Sound. This large crescent-shaped belt almost completely surrounds the 

 Great Basin. Practically nothing is known concerning the exact limits of 

 the ranges of the individual species, particularly the western ones, as the 

 collections are in most cases very meager. The species on the whole are 

 plants of the lower altitudes, not a few being marsh plants. 



Key to the Species 



I. Receptacle comparatively shallow ; follicles spreading and often apparently superior 

 at maturity 



A. Petals narrowly lanceolate 



a. Follicles and beaks elongate 



1. Petals white ; follicles green 



(a) Branches of inflorescence diffuse and delicate S. Forbesii 



(b) Branches of inflorescence stout, ascending S. pennsylvanica 



2. Petals purple S. purpuripetala 



b. Follicles globose, inflated; brownish 



1. Follicles large, stout ; beaks thick S. crassicarpa 



2. Follicles small ; beaks very short 5". winnebagoensis 



B. Petals orbiculate to oblong 



a. Leaves elongate, of a lanceolate type ; tall species 



1. Leaves narrowly lanceolate or oblanceolate ; petals oblong S. oregana 



2. Leaves broader and mostly shorter; petals ovate or orbiculate .. 5". Sierrae 



