380 CARDUACEAE. 



68. CHAMAECHAENACTIS Rydb. 



i. Chamaechaenactis scaposa (Eastw.) Rydb. (Chaenactis scaposa Eastvv.) 

 In arid regions of Utah and Colo. Grand Junction. 



69. RYDBERGIA Greene. 



Involucres densely white-woolly at the base ; basal leaves more or less doubly 

 pinnatifid. i. R. grandiflora. 



Involucres darker, short-villous at the base ; leaves simply pinnatifid with few 

 divisions. 2. R. Brandegei. 



1. Rydbergia grandiflora (T. & G.) Greene. (Actinella grandiflora T. & G.) 

 On high mountain sides from Mont, to N. M. and Calif. Alt. 9000-13,500 

 ft Alpine Tunnel; Pike's Peak; Ironton, San Juan Co.; Gray's Peak; 

 Mt. Harvard; Mt. Abram, Ouray; Seven Lakes; mountains south of Ward, 

 Boulder Co.; Little Kate Mine, La Plata Mountains; near Pagosa Peak; 

 Floral Mountain, near Georgetown; mountains above Como; Carson; Cam- 

 eron Pass ; Berthoud -Pass ; Beaver Creek ; mountain northwest of Como ; 

 mountains about Graymont; Massif de 1'Arapahoe; Hinsdale Co.; headwaters 

 of Clear Creek; Ethel Peak. 



2. Rydbergia Brandegei (A. Gray) Rydb. (Actinella Brandegei A. Gray; 

 Rydbergia glabrata Greene) On high peaks of southern Colo, and N. M. 

 Alt. 9000-13,000 ft West Spanish Peak; Sierra Blanca. 



70. HYMENOXYS Cass. COLORADO RUBBER PLANT. 



Plant low, perennial with a multicipal caudex. 



Heads mostly solitary at the ends of the branches. 



Rays 12-18 mm. long; plant 1-3 dm. high. i. H. macrantha. 



Rays 5-8 mm. long; plant less than i dm. high. 2. H. pumila. 



Heads mostly corymbose. 



Rays orange, broadly cuneate. 3. H. Earlei. 



Rays yellow, oblong or somewhat cuneate. 4. H. floribunda. 



Plant tall, 3 dm. high or more, biennial or short-lived perennial, with one or 



few stems from a tap-root. 

 Stem simple below ; leaves pinnate or simple ; disk over i cm. wide. 



5. H. helenioides. 

 Stem diffusely branched ; leaves once to thrice ternate ; disk 5-8 mm. wide. 



6. H. multifiora. 



1. Hymenoxys macrantha (A. Nels.) Rydb. (Picradenia macrantha A. 

 Nels. ; H. Richardsonii macrantha Cockerell) In dry soil from Wyo. to Utah 

 and Colo. Como; South Park. 



2. Hymenoxys pumila (Greene) Rydb. (Picradenia pumila Greene; H. 

 Richardsonii pumila Cockerell) Very dry hills from Ass. to Colo, and Utah. 

 North Park. 



3. Hymenoxys Earlei Cockerell. In the pinon belt of Colo. Mancos. 



4. Hymenoxys floribtmda (A. Gray) Cockerell. (Actinella Richardsonii 

 fioribunda A. Gray; Picradenia floribunda Greene) In dry or gravelly soil 

 from Colo, to N. M. and Ariz. Alt 4000-10,000 ft Como; Buena Vista; 

 Marshall Pass; Placer; Westcliffe; Twin Lakes; Mancos; Gunnison; Sangre 

 de Cristo Creek; Turkey Creek and tributaries; Mt Harvard; dry plains 

 south of Antonito ; Dillon Canon ; Nepesta ; Colorado Springs. 



