458 RypBeERG: Rocky MOuNTAIN FLORA 
mm. broad, the less numerous rays, and the short and crowded 
leaf-segments. It belongs to the higher Rocky Mountains. 
ACHILLEA BOREALIS Bong. Veget. Sitcha 149. 1832 
In many respects this is close to the typical Achillea Mulle- 
folium. The heads are usually larger and have more rays; the 
bracts are usually darker but not always so. The main differences 
are in the inner bracts, which are decidedly acute, the narrow 
and usually long segments of the leaves, the rachis, which is 
almost without a wing margin, and the longer pubescence. The ~ 
leaves resemble much those of A. occidentalis and A. californica. 
The range of A. borealis extends from the Mackenzie to Alberta, 
British Columbia, and Alaska. The plant of Newfoundland and 
Labrador, which has been referred to this species is somewhat 
different. So far as I know, it has not received any specific name, 
but it has been described under the following name: | 
ACHILLEA MILLEFOLIUM NIGRESCENS E. Meyer, Pl. Labrad. 
65. 1830 
It has the large heads and dark-margined bracts of A. borealis, 
but the bracts are not acute, the leaf-segments are broad and 
short, and the rachis has a decided wing-margin. It agrees there- 
fore in every respect with A. Millefolium, except the larger head 
and the more numerous flowers. 
ACHILLEA CALIFORNICA Pollard, Bull. Torrey Club 26: 369. 
1899 
This, so far as I know, is not found in the Rocky Mountain 
region. It is restricted to the Pacific Coast. It is usually taller 
and more robust than any of the species mentioned above. The 
character of the head is practically the same as in A. Millefolium, 
but the heads are larger, about as large as in A. borealis. The 
margins of the bracts are usually not so dark as in that species 
and none of the bracts are acute. The leaf-form is more that of 
A. borealis and A. occidentalis, but the segments are usually still 
more elongated and more divaricate. The leaves are usually 
thrice rather than twice pinnatifid. 
