[From the HiriLKiiN of the Tdkkev Botanical Club, 37 : 541 557. 1910 ] 



Studies on the Rocky Mountain flora — XXIV 



Per Axel Rydberg 



Saussurea densa (Hook.) Rydb. sp. nov. 

 Saussurea alpina densa Hook. Fl. Bor.-Am. 1: 303. 1833. 

 Saussurea alpina Ledebouri A. Gray, Syn. Fl. 1^: 397. 1884. 



Not S. Ledebouri Herder, 18 10. 



Saussurea Ledebouri Herder was based on 5. subsinuata, 

 S. nuda, and S. Tilesii of Ledebour, which Herder united into one 

 species under another name. All three are illustrated in Lede- 

 bour's Icones Fl. Ross., and it is evident that 5. alpina densa 

 Hook, is different from each of them. None of the three illus- 

 trations shows the elongated, acuminate outer bracts, character- 

 istic of S. densa. Only S. nuda shows a dense inflorescence with 

 subsessile heads and a low stem, but the heads are fewer and less 

 crowded, the stem is naked above, and the leaves entire. 



S. densa is a plant of the higher mountains of the Canadian 

 Rockies. 



Saussurea remotiflora (Hook.) Rydb. sp. nov. 

 Saussurea alpina remotiflora Hook. Fl. Bor.-Am. 1: 303. 1833. 

 Saussurea alpina A. Gray, Syn. Fl. 1-: 396, in part. 1884. 

 Saussurea nuda Britt. & Rydb. Bull. N. Y. Bot. Gard. 2: 187. 



1901. Not. 5. nuda Ledeb. 1829, 



This species is nearer to Saussurea subsinuata Ledeb. than to 

 either 5'. alpina or S. nuda, but the inflorescence is laxer and the 

 involucre is different, judging from Ledebour's illustration. S. 

 remotiflora grows on low ground from northern Saskatchewan to 

 Yukon and Alaska. 



Carduus 

 So many species of thistles have lately been described from 

 the Rocky Mountains that the number has more than doubled 

 since the issue of Gray's Synoptical Flora. Some of these species 

 should be reduced to synonymy and some of them are probably 

 hybrids, but I think that the larger number will remain as good 



541 



