1919J Hall: Chrysothanuius nmiscosus and Its Varieties 173 



12. Chrysothamnus nauseosus var.glareosus (M.E.. Junes) comb. nov. 



Bigelovia glarcosa M. E. Jouos, Zoe, vol. 2. p. 247, 1891. 



Shrub many-stemmed, said to be only about 3 dm. high : leaves 

 broadly linear, slightly widened above, plane : inflorescence cymose : 

 bracts about 4 in each vertical row, somewhat keeled, obtuse, sparsely 

 erose-ciliate, scurfy-tomentulose : corolla about 12 mm. long ; lobes 

 linear-lanceolate : akenes glabrous. 



This variety is apparently restricted to central and southern Utah, 

 where it grows on gravelly mesas. It was originally compared with 

 leiospermus, from which it differs in the tomentulose involucre and 

 other characters. 



13. Chrysothamnus nauseosus var. leiospermus (Gray) comb. nov. 



Bigelovia leiosperma Gray, Syn. Fl., vol. 1, part 2, p. 139, 1884. 



Shrub low (3 to 12 dm. high), with numerous short erect twigs, 

 these either moderately leafy or almost naked : twigs yellowish green 

 with a verA' close tomentum : leaves filiform or nearly so, acute, mostly 

 0.5 to 2 or 3 cm. long, essentially glabrous : lieads in close terminal 

 cymes of 2 or 3 cm. diameter : involucre 6 to 8 mm. high : bracts 

 linear-oblong except the short ovate outer ones, obtuse, glabrous : 

 corolla 5 to 8 mm. long, the tube very obscurely pubescent (or 

 glabrous?) ; lobes ovate, erect, glabrous, 0.5 mm. or less long: akenes 

 completely glabrous in the typical form but often sparsely pubescent, 

 especially along the prominent nerves. 



This form inhabits the most arid portions of the Great Basin, 

 growing mostly on very dry exposed hillsides or in dry rocky stream- 

 ways. The only collections seen by the writer are from Clear Creek 

 Caiion, Utah, Candelaria in western Nevada, and Caliente in eastern 

 Nevada. The Clear Creek specimens formed the basis of Bigelovia 

 leiosperma var. ahhreviata M. E. Jones, Proc. Calif. Acad. Sci., ser. 

 2, vol. 5, p. 693, 1895, a form with scant tomentum and leaves 1 em. 

 or less long. The Caliente specimens (H. M. H., nos. 10791, 10795) 

 represent an extremely xerophile type of very dry exposed hillsides 

 in the Lower Sonoran Zone. Their stems are green and rush-like, 

 and the leaves reduced to scales about 3 mm. long, or rarely developed 

 and then about 1 cm. long. In one of the Caliente specimens the 

 akenes are very sparsely pubescent on the edges ; in another from the 

 same station they are sparsely pubescent also on the intervals. This 

 indicates that the absence of pubescence cannot be satisfactorily used 

 as a specific character. The relation.ships of leiospermus are probably 

 with Bigelovii. 



