34 Nelson : New Plants from Wyoming 



the enlarged crown of the caudex would be thoroughly diagnostic^ 

 but E. luteus has a caudex that is itself much branched and 



■ 



caespitose. 



Collected on a stony, gravelly hillside near Junction Butte, 

 no. 5741, and on gravelly bars on Soda Butte Creek, no. 5852 ; 

 both from Yellowstone Park, July 9, 1899. 



j 



Artemisia rhizomata 



Perennial from rather slender, horizontal, semi-woody rhiz- 

 omes, white or grayish tomentose throughout : stems rather numer- 

 ous, slender, ascending or nearly erect, simple but for short foliose 

 shoots in the axils of the leaves : leaves entire (rarely incised), 

 linear-oblong to lanceolate, 2-4 cm. long : those of the short ax- 

 illary shoots crowded and much smaller, only 1-2 cm. long : in- 

 florescence paniculate, consisting of a succession of axillary, spike- 

 like, nearly simple racemes which are crowded and naked above, 

 the lower axillary shoots mostly sterile but sometimes all florifer- 

 ous : heads oval or campanulate, about 4 mm. high and 20 flow- 

 ered, of which nearly half are female, some of the disk flowers ap- 

 parently not maturing akenes : akenes oblong, smooth, about 1.5 

 mm. long. 



The only species in this range with which this is comparable 

 is A. Ludovicana, but the habit and leaf characters, and its rather 

 unusual inflorescence, clearly separate it. Its rhizomes, too, are 

 peculiar. A. Ludoviciana occurs on dry ravine banks among the 

 hills, while this is found on low saline flats adjacent to streams. 

 First collected on the Sweetwater, Sept. 9, 1894, no. 1181, and 

 distributed as A. Mexicana Willd., though to this it bears little 

 resemblance. Since collected at Laramie also. 



x Artemisia rhizomata pabularis 



More slender^than the species with more numerous, erect stems : 

 the more slender rhizomes freely spreading just below the surface 

 of the soil : leaves crowded, nearly linear, more or less incisely 

 toothed at apex, 3-5 cm. long : the axillary, spicate flower clus- 

 ters shorter and more crowded : flowers fewer (about 1 5) nearly 

 all hermaphrodite. 



This is probably a good species, but as I have but one collec- 

 tion of it, it may stand as a variety until it has again been studied 

 in the field, it was secured in the Red Desert, near Creston, Aug. 

 29, 1897, no. 4426, in a saline draw, where it was growing freely 



