376 CARDUACEAE. 



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

 and Ariz. Alt. 4500-7000 ft. Brantly Canon, 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. 2. 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 Finos ; 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. PERICOME A. Gray. 



i. Pericome caudata A. Gray. In canons and river valleys from Colo, to 

 Tex. and N. M. ; also in Mex. Alt. 5000-8000 ft. North Cheyenne Canon; 

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



59. HYMENOPAPPUS 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. 



1. H. arenosus. 

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



2. H. cinereus. 

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



3. H. filifolius. 

 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. macroglottis. 

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



5. H. parvuhis. 



i. 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. 



