376 CARDUACEAE. 



4. Thelesperma subnudum A. Gray. On dry plains of Colo., Utah, N. M. 

 and Ariz. — Alt. 4500-7000 ft. — Brantly Cafion, Las Animas Co. ; Grand Junc- 

 tion ; Cedar Hills ; Walsenburg ; dry hills about Antonito. 



5. Thelesperma gracile A. Gray. On dry plains from Neb. and Colo, to 

 Tex. and Ariz. — Alt. 4000-10,000 ft. — Colorado Springs ; near Boulder ; Mani- 

 tou ; New Windsor ; Denver ; Ft. Collins ; between Sunshine and Ward ; Fos- 

 sil Creek; Wray; Raton Range; Poudre River. 



56. MADIA Molina. Tar-weed. 



I. Madia glomerata Hook. In open dry places in the mountains from 

 Sask. and B. C. to Colo. — Alt. 6500-9000 ft.- — Valley near Empire ; Rabbits-Ear 

 Pass ; Cerro Summit ; Pagosa Springs ; Gunnison Co. ; Hubbard Creek ; Dale 

 Creek ; Steamboat Springs ; between Pallas and Sydney ; Hotchkiss ; Hayden. 



Tribe 5. HELENIAE. 



57. PSILOSTROPHE DC. 



Scales of the pappus one-third as long as the disk-corollas, mostly obtuse ; leaves 

 broadly spatulate ; rays 8-12 mm. long, indistinctly nerved. i. P. Bakeri. 



Scales of the pappus one-half as long as the disk-corollas, acute or acuminate ; 

 rays 5-8 mm. long, distinctly veined. ^. P. tagetina. 



1. Psilostrophe Bakeri Greene. {Riddellia tagetina pumila Jones ; P. pumila 

 A. Nels.) On dry plains and hills in Colo, and Utah. — Alt. 5500 ft. — Uncom- 

 pahgre Mountains, near Los Pinos ; Rifle, Garfield Co. ; Grand Junction ; 

 Delta Co.; Montrose; Hotchkiss; Palisades. 



2. Psilostrophe tagetina (Nutt.) Greene. {Riddellia tagetina Nutt.) On 

 dry plains from Colo, to Tex. and Ariz. — Sources of the Platte. 



58. PEHICOME A. Gray. 



I. Pericome caudata A. Gray. In caiions and river valleys from Colo, to 

 Tex. and N. M.', also in iKex.— Alt. 5000-8000 ft.— North Cheyenne Caiion; 

 Manitou; Engelmann Caiion; Colorado Springs; Marshall Pass; Ute Pass. 



59. HYMEWOPAPPtrS L'Her. 



Throat of the corolla 1-1.5 mm. long, not over twice as long as the lobes. 

 Pappus not hidden by the hairs of the achenes. 



Stem permanently densely white-tomentose ; achenes silky. 



I. H. arenosus. 

 Stem sparingly grayish-tomentose, glabrate in age; achenes loosely villous. 



n. H. cinereus. 

 Pappus hidden by the hairs of the achenes, or sometimes none. 



3. H. aiifolius. 

 Throat of the corolla 3-4 times as long as the lobes. 



Pappus shorter than the corolla-tube ; throat of corolla 3-4 mm. long ; plant tall. 



4. H. macrogloifis. 

 Pappus equalling the corolla-tube; throat about 1.5 mm. long; plant dwarf. 



5. H. parvulus. 



1. Hymenopappus arenosus Heller. On dry hills and plains from Colo, and 

 Utah to N. M.— Alt. 5000-7000 ft.— Arboles; Dolores; hills above Trinidad; 

 Grand Junction ; Mancos ; Florence. 



