RYDBERG: Rocky MOUNTAIN FLORA 455 
' Artemisia Herriotii sp. nov. 
Perennial with a rootstock; stem 6-10 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; 
r 
small heads; branches erect, racemiform; heads erect; involucres 
about 5 mm. high, 2.5—3 mm. 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. latiloba 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, Macoun & Herriot 
72825 (type, in herb. N. Y. Bot. Gard.). 
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. multiflora, 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. 
lanulosa Nutt. as variety of A. Millefolium. Robinson and Fer- 
nald+ regarded A. lanulosa as a good species. Pollard { admitted 
10 species as North American. Of these one is Mexican and three 
escaped or introduced. Afterwards he, in codperation with 
Cockerell,§ described an additional species from New Mexico. 
ith the wes of A. multiflora and perhaps A. laxiflora, 
*Contr. U. S. Nat. Herb. vol. 11. 
TtGray’s Neg Manual 8 
tBull. Torrey Club 26: ake 375. 1899. 
§Proc. Biol. Soc. Wash. 15: 179. 1902. 
