C. DEPRESSUS. 



195 



first by Gray (Pacif. R. R. Rep. 4<:98, 1857) and later in all manuals in which it was 

 treated. It is very clear, however, that the two are not closely related and that bigelovi 

 is a subspecies of C. nauseosus. The evidence has been stated in a previous paper (Hall, 

 Univ. Calif. Publ. Bot. 7:172, 1919). 



The three subspecies are much closer in their affinities to one another than any one 

 of them is to depressus. Their differences are only such as habit, width of leaf, and 

 amount of pubescence. Subspecies baileyi is very close to lypicus, the only dependable 

 difference being the scabrid-ciliate leaf margins. A majority of the specimens in herbaria 

 under pulchellus have this character, but it is often so poorly developed as to be over- 

 looked, as, for example, in Havard's Texan collection cited above. According to 

 Standley (Proc. Biol. Soc. Wash. 26:119, 1913), elatior differs decidedly in habit as well 

 as in pubescence, and further field studies may warrant its recognition as a species. 

 ECOLOGY AND USES. 



Chrysothamnus pulchellus is an undershrub, which occurs sparsely in subclimax areas 

 with C. n. bigelovi, Muhlenbergia pungens, etc., and persists for a time after Bouteloua 

 gracilis becomes dominant. No uses are known. 



Table 20. — Variation in Chrysothamnus pulchellus. 



9. CHRYSOTHAMNUS DEPRESSUS NuttaU, Jour. Phila. Acad. H, 1:171, 1847. Plate 29. 



Shrub or undershrub, 1 to 3 dm. high, forming dense clumps, irregularly much 

 branched, the lower branches decumbent; bark of old stems gray or brown; twigs brittle, 

 numerous, short, densely cinerous with a minute scabrous pubescence, striate; leaves 

 oblanceolate or spatulate, acute, erect, 0.8 to 2 cm. long, 1 to 4 mm. wide, 1-nerved, 

 rigid, finely puberulent like the twigs; heads in small compact terminal cymes; involucre 

 9 to 12 mm. high; bracts 20 or 25, in 5 sharply defined vertical ranks, boat-shaped, 

 keeled, attenuate to a short mucro or soft awn, commonly brown on the back, minutely 

 rough-puberulent on the exposed parts; flowers 5; corolla tubular-funnelform, the tube 

 passing gradually into the slightly broader throat, 7 to 9 mm. long, glabrous; lobes 

 lanceolate, 1 to 2.3 mm. long, nearly erect, glabrous; anther-tips lanceolate, very acute, 

 about 0.5 mm. long; style-branches exserted, the comparatively thick appendage only 

 slightly exceeding or usually shorter than the stigmatic portion; achenes nearly pris- 



