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 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. 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. arena sus. 

 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. //. macro glottis. 

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



5. H. parvulus. 



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. 



