190 GENUS CHRTSOTHAMNUS. 



Gutierrezia, with which they are often associated. Pumilus is also very common in 

 sagebrush areas, and is often dominant in bleared areas. Puberulus and stenophyllus 

 are chiefly found in the sagebrush association, especially on the poorer soils and in dis- 

 turbed areas. 



Linifolius is the only subspecies to grow regularly in strongly alkaline soil, even being 

 associated on alkali flats and creek bottoms with Sarcobatus. However, pumilus is 

 frequently found with such halophytes as Atriplex confertifolia and A. nuttalli, and 

 stenophyllus may occur with A. confertifolia, Sporobolus airoides, and others. 



USES. 



All of the variations of C. viscidiflorus are browsed to a limited extent by sheep and 

 perhaps also by cattle. Some stockmen report the plants as of no value, but this applies 

 only to districts where other feed is fairly plentiful. Throughout the Great Basin, 

 and especially from Inyo County, California, to eastern Washington, the shrubs furnish 

 good sheep-feed, the animals relishing especially the flowering shoots. Three of the 

 subspecies have been examined for rubber with negative results. In linifolius, however, 

 rubber was found to be present to the extent of 1 per cent of the dry weight. This is not 

 sufficient to be of more than passing interest. It is perhaps correlated with the alkaline 

 habitat, since in C. nauseosus it is found that the highest rubber-content occurs in those 

 forms which inhabit alkaline soils. If this is a law of general application in the genus, 

 then the other subspecies of C. viscidiflorus could not be expected to yield rubber, since 

 none of them grows in alkaline situations. 



6. CHRYSOTHAMNUS GREENEI (Gray) Greene, Erythea 3:94, 1895. Plate 28. 



Shrub 1 to 3 dm. high, bushy, much branched from the base; bark of basal portion 

 brown, fibrous, peeling off in sheets; twigs very brittle, erect and congested, glabrous, 

 at first green but soon white and shining; leaves narrowly linear or nearly filiform, 

 pungently acute, 1 to 3.5 cm. long, 0.3 to 1.2 mm. wide, 1-nerved, rigid, either nearly 

 glabrous or only sparsely and minutely scabrous-ciliate, more or less viscidulous; heads in 

 terminal rounded or flat-topped cymes; involucre 5 to 7 mm. high; bracts 15 to 20, in 

 5 poorly defined vertical ranks, oblong, abruptly narrowed to a subulate tip or the outer 

 ones more gradually attenuate, glabrous but viscidulous; flowers 5; corolla (whitish or 

 yellow) tubular-funnelform, the throat abruptly dilated, 4 to 4.5 mm. long, glabrous; 

 lobes lanceolate, 0.8 to 1.3 mm. long, spreading, glabrous; anther-tips lanceolate, acute, 

 about 0.5 mm. long; style-branches exserted, the appendage much shorter than the 

 stigmatic portion; achenes nearly prismatic, about 3 mm. long when mature, densely 

 appressed-villous; pappus rather scant and rigid, scarcely equaling the corolla, dull white. 

 {Bigelovia greenei Gray, Proc. Am. Acad. 11 :75, 1876.) 



Plains and low hills from southern Colorado to New Mexico, Arizona, Nevada, and 

 Utah. 



SUBSPECIES. 



C. greenei exhibits a tendency to break up into two divergent groups of forms, as 

 follows : 



Key to the Subspecies of Chrj/sothamnus greenei. 



Leaves mostly 2.5 to 3.5 cm. long, 1 mm. or more wide (a) typicus (p. 190). 



Leaves mostly less than 2 cm. long, less than 1 mm. wide (b) filifolius (p. 191). 



6a. Chrysothamnus greenei typicus. — Plant low and stout; leaves narrowly linear, 

 usually 2 to 3.5 cm. long and about 1 mm. wide, usually dark green; heads in loose cymes, 

 mostly on distinct peduncles; involucre 5.2 to 7.0 mm. high, 2 to 3 mm. broad. (C. 

 greenei Gray, Proc. Am. Acad. 11:75, 1876.) Southern Colorado, Utah, and eastern 

 Nevada. Type locality, Huerfano Plains, southern part of Colorado. Collections 

 (these are cited in table 19). 



