Rydbekg : Rocky Mountain flora 455 



Artemisia Herriotii sp. nov. 



Perennial with a rootstock; stem 6-io dm. high or more, 

 tomentose; leaves entire or sparingly and sharply toothed, 5-20 

 cm. long, 5-15 mm. wide, glabrate and green above, densely 

 white-tomentose beneath, rather thin, margins not revolute; 

 inflorescence a narrow compact panicle with very numerous 

 small heads; branches erect, racemiform; heads erect; involucres 

 about 5 mm. high, 2.5-3 nim. broad; bracts oblong-ovate to ovate, 

 acute or obtuse, yellowish, densely tomentose; flowers yellow, the 

 central ones fertile; receptacle naked. 



Bourgeau's specimens were referred to Artemisia longifolia 

 by Dr. Gray, but they are not closely related to that species. The 

 leaves are not revolute-margined and the heads are not half the 

 size of those of that species. It is most closely related to A. silvi- 

 cola and A. Hookeriana Besser (A. latiloha Rydb.). It differs 

 from the former in the denser and narrower inflorescence, the erect 

 heads, the denser tomentum on the involucres, and the firmer 

 leaves, and from the latter in the more entire leaves and the 

 smaller, more cylindric heads. 



Alberta: Edmonton, Aug. 25, 1906, Macoiin & Herriot 

 72825 (type, in herb. N. Y. Bot. Card.). 



Saskatchewan: 1858, Bourgeau (in herb. Gray). 



Achillea 



A great diversity of opinion exists among botanists as to the 



number of species of this genus found in America. Dr. Gray 



admitted three species, Achillea Millefolium, A. midtijlora, and A. 



Ptarmica. Evidently Nelson held the same view, as he admits 



only A. Millefolium, the other two not being found in the Rocky 



Mountain region. Piper in his Flora of Washington* admitted A. 



laniilosa Nutt. as variety of A. Millefolium. Robinson and Fer- 



naldf regarded A. lanulosa as a good species. Pollard t admitted 



10 species as North American. Of these one is Mexican and three 



escaped or introduced. Afterwards he, in cooperation with 



Cockerell,§ described an additional species from New Mexico. 



With the exception of A. multifiora and perhaps A. laxiflora, 



*Contr. U. S. Nat. Herb. voL ii. 

 tGray's New Manual 845. 

 JBuU. Torrey Club 26: 365-375- i899- 

 §Proc. Biol. Soc. Wash. 15: 179. 1902. 



