CARDUACEAE. 343 



21. Chrysothamnus serrulatus (Torr.) Rydb. (Bigelovia Douglasii ser- 

 rulata A. Gray; C. glaucus A. Nels.) On dry plains of Wyo. and Utah to 

 Colo. Alt. 5000-8000 ft. Gypsum ; road to Steamboat Springs ; Cottonwood 

 Lake ; South Park, near Jefferson ; North Park ; headwaters of Clear Creek ; 

 Twin Lakes ; Middle Park. 



22. Chrysothamnus latifolius (D. C. Eaton) Rydb. (Bigelovia Douglasii 

 latifolia A. Gray) On dry plains from Mont, and Wash, to Colo. 



23. Chrysothamnus lanceolatus Nutt. (Bigelovia Douglasii lanceolata A. 

 Gray) On dry plains and hills from Mont, and Wash, to Colo. Alt. 7000- 

 8500 ft. Cottonwood Lake; Grizzly Creek; Black Canon; Cerro Summit; 

 North Park, near Walden ; Hayden, Routt Co. 



24. Chrysothamnus puberulus (D. C. Eaton) Greene. (Linosyris viscidi- 

 flora puberula D. C. Eaton) On dry plains and hills from Mont, and Wash, 

 to Colo, and Utah. Alt. 8000-9500 ft. Pitkin ; Parlin ; South Park, south- 

 east of Jefferson. 



25. Chrysothamnus Vaseyi (A. Gray) Greene. (Bigelovia Vaseyi A. Gray) 

 In the mountains of Wyo., Colo, and Utah. Alt. about 7500 ft. Middle 

 Park; Greene, North Park; Gunnison; Squaw Hill, above Cimarron. 



10. ISOCOMA Nutt. 



Bracts acute, linear-lanceolate. i. I. pluriflora. 



Bracts obtuse or obtusish, linear, oblong or oblanceolate. 2. I. Wrightii. 



1. Isocoma pluriflora (T. & G.) Greene. (Bigelovia pluriflora A. Gray) 

 On plains of Colo. " On the Arkansas." 



2. Isocoma Wrightii (A. Gray) Rydb. (Bigelovia Wrightii A. Gray) On 

 banks and in saline soil from Colo, to Tex. and Ariz. Alt. 4000-5000 ft. 

 San Juan Valley (Brandegee). 



ii. SIDERANTHUS Nutt. 



Leaves spinescently toothed, not pinnatifid. 



Heads discoid; perennial with woody caudex. i. 5". grindelioides. 



Heads radiate ; annual. 2. S. annuus. 

 Leaves pinnatifid at least the lower ones. 



Stem more or less floccose or cinereous, especially when young. 



Plant cinereous-pubescent, more or less glandular. 3. 5. australis. 



Plant more or less floccose, not at all glandular. 4. S. spinulosus. 

 Plant neither floccose nor cinereous. 



Plant glabrous or slightly glandular-puberulent. 5. 5". glaberrimus. 

 Plant decidedly pubescent. 



Plant finely puberulent. 6. 5". puberulus. 



Plant hispid-strigose. 7. S. gracilis. 



1. Sideranthus grindelioides (Nutt.) Britton. (Aplopappus Nuttallii T. 

 & G.) On dry plains and hills from Ass. and Nev. to Neb. and Ariz. Alt. 

 4000-5500 ft. Grand Junction; Rifle; Hotchkiss. 



2. Sideranthus annuus Rydb. (Aplopappus rubiginosus A. Gray; not T. 

 & G.) On sandy soil from Neb. and Colo, to Kans. and Tex. Alt. 4000- 

 5000 ft. Platte Valley, Julesburg ; New Windsor ; Ft. Collins. 



3. Sideranthus australis (Greene) Rydb. (Aplopappus australis Greene) 

 On dry soil from Colo, to Tex. and N. M. ; also in Mex. Alt. about 4700 ft. 

 Deer Run. 



