494 



COMPOSITAE (COMPOSITE FAMILY) 



bescence softly silky-canescent throughout: leaves spatulate-oblong or oblong 

 and sessile: heads few to many, corymbose; bracts of the villous-canescent 

 involucre narrowly linear-lanceolate: outer pappus minute. Plains of the 

 upper Platte. 



9. CHRYSOTHAMNUS Nutt. RABBIT BRUSH. 



GOLDENROD 



RAYLESS OR FALSE 



1. C. linifolius. 



2. C. glaucus. 



3. C. pumilus. 



4. C. Greenei. 



5. C. lanceolatus. 



6. C. Vaseyi. 



7. C. depressus. 



Shrubby or suffrutescent plants with narrow or terete entire leaves. Her- 

 bage white-tomentose or glabrous, often viscidulous or resinous. Inflores- 

 cence paniculate, cymose, or rarely racemose. Heads homogamous. In- 

 volucre narrow; the bracts well imbricated usually in more or less distinct 

 vertical ranks, chartaceous or coriaceous, mostly destitute of herbaceous tips. 

 Ray-flowers uniformly wanting; disk-flowers 5-30. Style-branches subulate 

 or filiform, usually long-exserted. Achenes narrow, terete or slightly angled, 

 pubescent. Pappus copious, soft, commonly dull white. Bigelovia. 



The entire plant wholly devoid of tomentum. 



Tall (5-10 dm.); branchlets slender-virgate or stouter and fas- 



tigiate; leaves scabrous-margined. 

 Growing on the wet banks of alkali creeks (strikingly halophy- 



tic) 



Growing on dry hills, in soil free from alkali .... 

 Low (5 dm. or less); usually freely branched. 



Leaves glabrous but sometimes scabrous on the margins. 

 Leaves 3-nerved, often involute and twisted 

 Leaves 1-nerved, flat, ciliate on the margin 

 Leaves puberulent or scabrous, but often very minutely or 



sparingly so. 

 Bracts not acuminate, but often subacute. 



Achenes pubescent 



Achenes glabrous ........ 



Bracts firm and sharply acuminate ..... 



Tomentose, in some species densely so and in the others at least traces 



upon stems or leaves. 

 Branchlets permanently white-tomentose. 



Plant widely bushy-branched ...... 



Plant strict with erect branches ...... 



Branchlets either glabrate from the first or shedding more or less 



of their tomentum. 

 Involucral bracts acuminate or at least sharply acute, arachnoid- 



ciliate. 

 Achenes glabrous, ........ 



Achenes pubescent. 



Leaves linear, 1-nerved (in no. 12 sometimes surpassing 



the flowers). 

 Involucral bracts long-acuminate, somewhat divaricate, 



the upper usually exceeding the corolla. 

 Flowers yellow; bracts arachnoid-ciliate on the mar- 

 gins; leaves green, not surpassing the flowers 

 Flowers pale or dirty yellow; bracts lanate; leaves 

 pale or yellowish-green, the upper often longer 

 than the flowers ...... 



Involucral bracts merely acute, erect, shorter than the 

 corolla, arachnoid-ciliate; leaves canaliculate, 3-6 

 cm. long . . i. '.;'" 



Leaves broadly linear, 3-nerved, green, the upper surpass- 

 ing the flowers ........ 



Involucral bracts not acuminate, lanceolate and acute or nar- 

 rowly oblong and blunt. 



Bracts quite glabrous, not glutinous; leaves glabrous at ma- 

 turity; stems slender, erect, 4-6 dm. high . 

 Bracts erose-ciliate on the margin, or tomentose, or both, and 

 sometimes glutinous; some tomentum persisting on the 

 leaves. 



Plant 5-12 dm. high, with branched trunk-like base, the 

 season's sterns slender-virgate, erect .... 



Plant 2-5 dm. high, freely branched from the base. 

 Leaves almost filiform and widely divaricate 

 Leaves linear, mostly erect 



8. C. graveolens. 



9. C. nauseosus. 



10. C. Bigelovii. 



11. C. affinis. 



12. C. Howardii. 



13. C. wyomingensis 



14. C. Parryi. 



15. C. oreophilus. 



16. C. pulcherrimus. 



17. C. plattensis. 



;. pn 



J.fri 



18. C. frigidus. 



1. Chrysothamnus linifolius Greene, Pitt. 3: 24. 1896. Tufted, woody 

 stems erect, slender and flexible, 6-10 dm, high, fastigiately branching above, 



