C. PANICULATUS. 175 



Key to the Sections and Species of Chryaothamnua. 



Herbage resinous-punctate; leaves terete (Punctati). 



Bracts all pale, without greenish spot 1. C. -panicuLcUus (p. 175). 



Outer bracts with a distinct greenish subapical spot 2. C. teretifolius (p. 176). 



Herbage not resinous-punctate; leaves oblanceolate to narrowly linear or nearly terete. 

 Twigs glabrous or puberulent, not closely tomentose. 



Bracts moderately keeled, the vertical rows not sharply defined; achenes either 

 decidedly pubescent or glabrous and l6-striate (Typici). 

 Achenes glabrous or nearly so and 10-striate. 



Leaves lanceolate, 5 to 10 mm. wide, strongly 3- or 5-nerved; corolla 12 mm. 



long; ' style-appendages twice as long as the stigmatic portion . . 3. C. gramineua (p. 178). 

 Leaves linear or very narrowly oblanceolate, 1 to 2 mm. wide, 1-nerved; 

 corolla 7 mm. or less long; style-appendages scarcely exceeding 



or shorter than the stigmatic portion , 4. C. vaseyi (p. 179). 



Achenes densely pubescent or rarely sparsely so, but never striate. 



Involucral bracts obtuse to acute, but never slenderly acuminate 5. C. viscidiflorus (p. 180). 



Involucral bracts (some or most of them) slenderly acuminate or with an 

 abrupt mucro. 

 Corolla about 5 mm. long, yellow; anther-tips lanceolate, very acute, about 



0.5 mm. long 6. C. greenei (p. 190). 



Corolla 7 to 8 mm. long, whitish; anther-tips ovate, obtuse, about 0.2 mm. 



long 7. C. albidiis (p. 192). 



Bracts strongly keeled, the vertical rows very distinct; achenes glabrous or only 

 minutely pubescent, not striate (Pulchelli). 



Leaves fiUform to Unear; corolla 10 to 14 mm. long 8. C. pulchellus (p. 193). 



Leaves spatulate or oblanceolate; corolla 7 to 9 mm. long 9. C. depressus (p. 195). 



Twigs covered with a pannose or felt-like tomentum, this sometimes so close as to 



escape observation (Nadseosi). 



Heads in leafy spike-like or raceme-like clusters, these sometimes branching to form 



panicles; outer bracts of involucre commonly prolonged into 



a slender herbaceous tip or appendage (e.xcept in C. pyramidatus). 



Involucre about 6 mm. high; upper leaves fascicled 10. C. pyramidatus (p. 197). 



Involucre 10 to 15 mm. high; leaves not fascicled 11. C. parryi (p. 198). 



Heads cymose at the ends of the branches, the inflorescence sometimes compound 

 and elongated, bracts of the involucre obtuse to acute, the outer 

 ones regularly shortened and devoid of herbaceous tip 12. C. natiseosus (p. 209). 



Section I. PUNCTATI. 



1. CHRYSOTHAMNUS PANICULATUS (Gray) Hall, Univ. Calif. Publ. Bot. 3:58, 1907. 



Plate 24. 



Shrub 6 to 20 dm. high, with several or numerous main stems from the base, forming 

 a broad, rounded plant; bark of the older portions dark gray, rough; twigs brittle, 

 spreading, leafy, glabrous but resinous and viscid, at first green (or with a gray waxy 

 bloom) and impressed-punctate, later turning brown and striate; leaves terete, shortly 

 mucronate, 1 to 3 cm. long (much shorter in the inflorescence), glabrous but very resinous 

 and marked by numerous impressed resin-dots, sometimes with a gray waxy bloom; 

 heads in profuse terminal panicles or the inflorescence occasionally reduced and sub- 

 racemose but never spicate; involucre 5 to 6 mm. high; bracts 13 to 17, in 5 obvious but 

 not sharply defined vertical ranks, oblong, obtuse, not carinate, rather thin, glabrous, 

 stramineous, without apical spot; flowers 5 to 8; corolla tubular-funnelform, the tube 

 passing gradually into a much wider throat, about 6 mm. long, glabrous; lobes lance- 

 ovate, about 1 mm. long, nearly erect, glabrous; anther-tips linear, acute, 0.5 mm. 

 long; style-branches long-exserted, the appendage varying from only slightly to twice 

 longer than the stigmatic portion; achenes tapering from summit to base, 5-angled, 

 about 4 mm. long when mature, appressed- villous ; pappus scarcely equaling the corolla, 

 white. {Bigelovia paniculata Gray, Proc. Am. Acad. 8:644, 1873.) 



Arid and stony slopes, especially in dry streamways, from southwestern Utah across 

 northern Arizona to the Colorado and Mojave deserts in California as far west as 

 Tehachapi Pass; not common. Type locahty, California. Collections: Arizona, 1902, 



' Throughout the paper the length of the corolla is taken to include the lobea. All meaaurements are for fresh material 

 or for flowers restored by boiling. 



