492 Rydberg: Notes on Rosaceae 



sepals in length ; in 5. triflora the hypanthium at least in anthesis 

 is acute at the base and the bractlets much exceeding the sepals 

 in length. If so characterized, Sieverisa triflora takes in all the 

 forms growing on the prairies or plain region east of the Rockies 

 and extending into Montana and Wyoming. 



Erythrocoma cinerascens Greene and E. affinis Greene I can not 

 distinguish from it. The former is a depauperate form, I take to 

 be due to a higher altitude, represented by most specimens from 

 the Black Hills and Wyoming. The latter is the high northern 

 form with narrower leaflets and brighter coloration. If held 

 distinct it had two older names than that of Dr. Greene, viz. 

 Sieversia rosea Graham and Genm Grahami Steudel. 



Sieversia grisea (Greene) Rydb. The following proposed 

 species of Erythrocoma, viz. E. grisea, E. arizonica, E. tridentata 

 and E. aliena, all by Greene, have many characters common 

 with S. triflora, viz. the habit, leaf-form and toothing, pubescence, 

 and styles, but the hypanthium is not acute at the base, the petals 

 are broader and the bractlets shorter, slightly if at all longer than 

 the sepals. 



They were all described from Arizona and Chihuahua, but 

 the same forms are common in Colorado and rarely as far north 

 as Montana and Washington. They constitute the mountain 

 representatives of S. triflora. Of these Erythrocoma grisea is the 

 first one in the list. The type does not represent the common 

 form, but is a depauperate form with short leaves, standing in 

 the same relationship to the common form as E. cinerascens 

 Greene stands to Sieversia triflora. The common better-developed 

 form represents E. arizonica and is common in Colorado. E. 

 tridentata is a form with looser pubescence and narrower leaflets, 

 otherwise not distinguishable from E. arizonica. E. aliena is 

 exactly the same as E. grisea. 



Erythrocoma australis I regard as a hybrid between Sieversia 

 grisea and 5. ciliata. See my notes in the North American Flora. 



Sieversia canescens (Greene) Rydb. The forms of Erythro- 

 coma of the mountains of California, Oregon and Washington 

 differ very little from 6". grisea, as here understood, except in a 

 denser pubescence and shorter bracts. It is doubtful if they 

 should be regarded as a distinct species. I retained, although 



