RvDBERG : Studies on Rocky Mountain Flora 173 



and woody rootstock. The heads of ^. Nelsonii are larger, 8—10 

 mm. high, and the bracts are thin and in anthesis almost equal 

 the disk, while in vS. Fendlcri they are thick and much shorter. 

 The former also lacks the fine tomentum of the latter ; it is merely 

 floccose when young in the manner of 5. nudtilobatiis and .S". com- 

 pactiis. S. Nchonii is dark green while 5". Fcndleri is more or less 

 yellowish. Neither of the species forms mats, as Prof Greene 

 states. Heller's specimens, from the type locality of .9. Fcndleri, 

 agree fully with Gray's description of that species, except that the}- 

 are more glabrate than the type. They represent a plant of several 

 season's growth, but show nothing to indicate a matted plant. I 

 think that Prof Greene has here confused 5. rosidatus with the 

 two. Prof Greene's conception of ^. Fcndleri must be very com- 

 prehensive, indeed, as he also includes in that such forms as 6". 

 siibciuicatus, S. canovire?is, and another species, nearly related to 

 S. fastigiatiis Nutt. This statement is founded on specimens de- 

 termined by Prof Greene only a year or two ago and found in the 

 herbarium of the New York Botanical Garden. By comparing 

 Plate 5, Fig. 6, and Plate 6,' Figs, i, 3, 4 and 9, with each other, 

 one can get an idea of Prof Greene's conception of 6". Fcndleri. 

 I hav^e seen no specimens of S. Nelsonii except the type. 



AUREI 



Slender perennials, over 2 dm. high, with a short erect caudex 

 or rootstalk, glabrous or slightly floccose when young, the wool 

 remaining in age only at the oase of the leaves : basal leaves entire, 

 merely toothed : stem leaves more or less pinnatifid and the upper 

 more or less reduced : heads small, cymose, with very small and 

 few calyculate bracts. 



Heads radiate. 



Leaves thick, more or less fleshy. 



Basal leaves nan'owly oblanceolate. 



Plant low, less than 2 dm. high, often with several stems from the base; 

 basal leaves short-petioled. 

 Cyme dense ; upperleaves generally pinnatifid with narrow lobes. 



6. ^^ compactus. 

 Cyme more open ; stem leaves entire or merely crenate. 



Basal leaves subentire or 3-toothed at the apex. 



7. S. tridenticulatiis . 

 Basal leaves crenate. 8. S. oblanceolatus. 



