Rydberg: Notes on Rosaceae 493 



with hesitation, the specific rank of these forms, on which Erythro- 

 coma canescens Greene was based. 



Sieversia ciliata (Pursh) G. Don. This species is confined to 

 the Rocky Mountains and running down into the Cascades of 

 Washington. It is found neither on the plains nor in the Sierra 

 Nevadas. In most of its range it is associated with S. grisea and 

 intermediate forms are not lacking; they are perhaps to be ex- 

 plained as of hybrid origin. The center of its distribution is in 

 the northern Rockies, while that of 5. grisea is more common in 

 the southern. Its range barely touches that of S. triflora and 

 only slightly overlaps that of S. canescens. 



Sieversia flavula (Greene) Rydb. It was only with reluctance 

 I admitted this as a species in the North American Flora. It is 

 rather local in the mountains of Wyoming and Montana. The 

 following specimens have been seen. 



Wyoming: A. Nelson 82Q, 7501. 



Montana: Chestnut & Jones 105; Rydberg & Bessey 4414. 



Sieversia brevifolia (Greene) Rydb. This is a derivative of 

 S. ciliata. It is confined to the mountains of central Utah. S. 

 Watson 318, doubtfully referred here by Dr. Greene, I think should 

 be referred to S. ciliata. The following specimens belong here: 



Utah: Panguitch Lake, Jones 6oo2g; Fish Lake, Jones 577 'Qg, 

 54410; L. F. Ward 378. 



Sieversia Peckii (Pursh) R. Br. This and the three following 

 form a distinct natural group, which is represented in Europe by 

 Sieversia montana and other species. S. Peckii has been confused 

 with S. radiatum or has been made a variety of the same. It is, 

 however, perfectly distinct. It is confined to the mountains of 

 New Hampshire and Maine. 



Sieversia radiata (Michx.) R. Br. This is closely related to 

 the northwestern S. calthifolia (Menzies) D. Don. It is con- 

 fined to the region of which Roan Mountain is the center, and the 

 majority of the specimens in our herbaria are from that very 

 mountain. 



Sieversia calthifolia (Menzies) D. Don. This species is rather 

 variable. In the high arctic regions it becomes stunted and more 

 hairy (var. congesta), and then has a quite different appearance. 

 Another cause for the many synonyms cited under the species 



