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. subsquarrosa. 



Bracts not recur%'ed 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- Ctisickii. 

 Heads distinctly radiate. 



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



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 wholly 

 foliaceous. 

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



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



Stem and involucre almost glabrous ; bracts chartaceous at the base 

 with foliaceous tips. 9. P. integrifolia. 



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

 Bracts in 2-3 unequal series. 



Leaves 5-15 mm wide ; disk 1-2 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. teiiuicaulis. 

 Bracts nealrly of the same length. 



Stem-leaves oblanceolate ; bracts long-acuminate. 



13. P. acuminata. 

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



Plant villous. 14. P. imdoides. 



Plant, except the. upper parts, glabrate in age. 



15. P. unijlora. 

 Plant decidedly glandular. 16. P. hirta. 



I. Pyrrocoma subsquarrosa 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. sidnqiiarrosa was collected in northern 

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



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

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

 1863 : 65. 1864. 



