Figure 40. — Dwarf rabbi t- 

 brush (C. depressusJ 

 growing near the mouth 

 of Ephraim Canyon^ 

 Sanpete Co., Utah. 



Use. — Dwarf rabbitbrush is often heavily browsed by sheep, cattle, and wildlife 

 (Hall and Clements 1923). It transplants readily and is useful for stabilizing depleted 

 soils on which it readily grows. It is a source of protein when grasses and broadleaf 

 herbs have dried. 



Chrysothamnus greenei (Gray) Greene (Greenes rabbitbrush) 



Greenes rabbitbrush is a small highly branched shrub only 1 to 3.5 dm high. Its 

 glabrous brittle twigs are green at first but soon become white and shiny. Bark on the 

 lower branches often peels off in sheets (Hall and Clements 1923) . The nearly glabrous 

 or slightly scabrous-ciliate leaves are narrowly linear, 1 . 2 m or less wide, 1 to 3.5 

 cm long, and are more or less viscidulous. 



Flower heads normally contain 5 disc flowers in rounded or flat-topped cymes. The 

 involucral bracts are 5 to 7 mm long, arranged in 5 poorly defined vertical ranks, and 

 terminate in narrowly acuminate, greenish tips. The tubular to funnelform corollas may 

 be whitish or yellow and 4 to 4.5 mm long. Achenes are about 3 mm long and are covered 

 with dense, long, shaggy hairs. 



Greenes rabbitbrush has been divided into 2 subspecies, ssp. greenei and ssp. 

 filifolius by some authors (Hall and Clements 1923; Harrington 1954; and Kearney and 

 Peebles 1960). These authors separate ssp. filifolius from greenei by its normally 

 larger stature and shorter narrower leaves. We believe no subspecies should be recog- 

 nized because the purported subspecies (1) are chromatographical ly similar (McArthur 

 and others 1978) and (2) often occur in mixed populations. The chromatographic data 

 from McArthur and others (1978) further suggest that C. greenei could be considered a 

 subspecies of C. viscidiflorus rather than a separate species. Chrysothamnus greenei 

 closely resembles C. viscidiflorus , particularly ssp. stenophyllus . Both have a low, 

 bushy habit, white-barked stems, and short narrow leaves. Furthermore, the axillaris 

 form of stenophyllus has involucral bracts with attenuate tips (Anderson 1964) that 

 closely resemble those of C. greenei. We concur with Hall and Clements (1923) who felt 

 the similarity between C. greenei and C. viscidiflorus indicated a close genetic 

 relationship . 



Hybridization. — Chrysothamnus greenei has a chromosome number of 2n = 18 

 (Anderson 1966). Anderson (letter 3/30/76) believes C. viscidiflorus ssp. stenophyllus 

 form axillaris "may represent some sort of introgression of C. greenei into C. v. 

 stenophyllus. " 



41 



