623 Rydberg : Studies on the Rocky Mountain Flora 



Heads apparently discoid, the sterile rays being concealed in the pappus. 



Inner bracts recurved cuspidate. I. P. siibsqiiarrosa. 



Bracts not recurved cuspidate. 



Bracts oblong or oval ; heads hemispherical. 



Leaves and bracts more or less spinulose-toothed, the latter with a nar- 

 row scarious margin. 2. P. carthamoides. 

 Leaves and bracts not spinulose-toothed, the latter with a broad scarious 

 erose margin. 

 Pappus sordid ; plant almost glabrous. 3. P. rigida. 

 Pappus brownish red ; plant villous. 4. P. erythropappa. 

 Bracts lanceolate ; head campanulate-turbinate. 5. P. Cusickii. 

 Heads distinctly radiate. 



Bracts except the innermost obtuse, obovate or oblong. 6. P. ciocea. 



Bracts mostly acute or acuminate. 

 Plant not glandular. 



Heads large ; disk 2 cm. or more in diameter ; bracts in about 3 series. 

 Upper part of stem and involucre decidedly villous ; bracts w-holly 

 foliaceous. 

 Bracts oblanceolate, abruptly acute. 7. P. Clenientis. 



Bracts lanceolate, long-acute. 8. P. villosa. 



Stem and involucre almost glabrous ; bracts chartaceous at the base 

 with foliaceous tips. ' 9. P. integ7-ifolia. 



Heads smaller ; disk less than 2 cm. in diameter. 

 Bracts in 2-3 unequal series. 



Leaves 5-15 mm wide ; disk I-2 cm. wide. 



Inflorescence corymbiform ; bracts long-acute. 



10. P. lanceolata. 

 Inflorescence racemifomi ; bracts abruptly acute. 



11. P. Vaseyi. 

 Leaves 2-4 mm. wide ; disk I cm. or less wide. 



12. P. ieuiiicaiilis. 

 Bracts nearly of the same length. 



Stem-leaves oblanceolate ; bracts long-acuminate. 



13. P. actiminata. 

 Stem-leaves lanceolate ; bracts acute or short-acuminate. 



Plant villous. 14. P. imiloides. 



Plant, except the upper parts, glabrate in age. 



15. P. unijlora. 

 Plant decidedly glandular. 16. P. hirta. 



I. Pyrrocoma subsouarrosa Greene, Erythea, 3: 22. 1895 

 I have seen no .specimen of this species ; but the description 

 indicates a plant wholly unlike the other species of the Rocky 

 Mountains, that I do not hesitate in accepting it as a good spe- 

 cies. The type of P. siibsqiiarrosa was collected in northern 

 Wyoming, by Dr. J. N. Rose in 1893. 



2. Pyrrocoma carthamoides Hook. Fl. Bor. Am. i : 307. 1833 

 Aplopappiis carthamoides A. Gray, Proc. Acad. Sci. Phila, 

 1863 : 65. 1864. 



