454 Rydberg : Rocky Mountain flora 



lodes Nutt. This is of course a matter of individual opinion. 

 It is fully as good as the two Nelsonian species A. aromatica 

 and A. nova, which I am inclined to admit. 



Artemisia silvicola Osterhout and A. Bakeri Greene are made 

 varieties of A. mexicana. The former is, as stated before, related 

 to A. mexicana, but the latter is very hard to distinguish from the 

 original A. Wrightii. A. mexicana is not found in the Rockies 

 and not even near them. What goes under that name from New 

 Mexico and Arizona is mostly either A. neo-mexicana Greene or 

 A. microcephala Wooton. The latter extends into southern Utah 

 and Nevada. 



So many species have already been proposed in this genus 

 that it may seem a little hazardous and unnecessary to add more 

 to the already too large number. There are, however, two plants, 

 both collected by Bourgeau on the Palliser Expedition in Saskat- 

 chewan, that can not be included in the species known by me, so 

 that it seems better to give descriptions of them here. The second 

 one was rediscovered in Alberta by Macoun and Herriot. 



Artemisia Bourgeauana sp. nov. 



Perennial with a tap-root and short caudex; stem silky- 

 pubescent, more or less tinged with red, 3-4 dm. high; basal 

 leaves petioled, 4-6 cm. long, sericeous-canescent on both sides, 

 twice-pinnatifid with oblanceolate divisions; stem-leaves pin- 

 natifid with linear, crowded divisions, rather small; heads nu- 

 merous in a narrow panicle; involucres nearly 5 mm. wide, silky- 

 villous, yellowish and shining; bracts oval, broadly scarious- 

 margined ; flowers light yellow, the central ones sterile. 



This species is perhaps most closely related to Artemisia For- 

 ivoodii, having the same habit and leaf form, but the plant is more 

 silky and the heads are twice as broad, fully as large as in A. 

 spithamaea and A. canadensis. From the former it differs in the 

 numerous heads, compound inflorescence, yellow instead of 

 browai flowers, and taller stem. From A. canadensis it differs 

 in the compact inflorescence, the densely silky leaves, and broader 

 leaf-segments. 



Saskatchewan: 1857--9, Bourgeau (type, in herb. Columbia 

 University) . 



