276 CICHORIACEAE 



Involucres 10 mm. high, usually 5-flowered; upper leaves reduced. 2. L. juncea 

 Amiuals; involucres 10-15 mm. high. 3. L. rostrata 



18. PRENANTHELLA Rydb. l. P. exigua. 



19. NABALUS Cass. Rattlesnake-koot. 



Basal leaves oblanceolate or spatulate; Inflorescence hirsute. 1. N. racemosus. 



Basal leaves cordate, sagittate, or hastate ; inflorescence glabrous or puberulent. 



Leaves variously lobed or cleft ; heads nodding ; calyculate bracts ovate, very short. 



2. N. albus. 

 Leaves dentate; flowering heads not nodding; calyculate bracts linear, half as long as 

 the bracts proper. 3. N. sagittatus. 



20. CREPIS L. 



Plant neither canescent nor furfurascent ; heads hemispherical to turbinate. 



Involucres glabrous or tomentulose when yornig; neither hirsute nor glandular. 



Involucres and peduncles tomentulose, at least when young. 1. C. lomentulosa. 

 Involucres glabrous or slightly puberulent when young. 2. C. glauca. 



Involucres and peduncles hirsute or glandular or both. 

 Plant 3-10 dm. high; heads few or many. 



Leaf-blades oblanceolate or oblong to Unear-oblanceolate. 



Leaves long-petioled; petioles half as long to fully as long as the blades, 

 not winged. 

 Blades of the basal leaves broadly oblanceolate; stem usually with 1-2 



leaves; involucres over 1 cm. high. 3. C. petiolata. 



Blades of the basal leaves narrowly linear-lanceolate or Unear-oblanceo- 

 late; stem scapiform; involucres less than 1 cm. high. 



4. C. glaucella. 

 Leaves subsessile or with short winged petioles. 



Leaves glabrous or nearly so; Involucres with a few short hairs. 



5. C. perplexans. 

 Leaves hairy. 



Involucres more sparingly and usually short-hirsute; peduncles and 

 stem usually glabrous ; involucres less than 1 cm. high. 



6. C. runcinata. 

 Involucres, peduncles, and usually also the stem, copiously glandu- 

 lar-hirsute; Involucre over 1 cm. high. 7. C. plalyphylla. 



Leaf-blades obovate to elliptic; involucres and peduncles densely glandular- 

 hispid with long hairs. 

 Involucres over 1 cm. high; leaves hairy, 1.5-2 dm. long. 



8. C riparia. 

 Involucres 1 cm. or less high; leaves glabrous or nearly so. 



9. C deniiculata. 

 Plant 1-2 dm. high; heads solitary, rarely 2 or 3. 10. C. alpicola. 



Plant more or less canescent or furfurascent, especially the leaves ; heads mostly narrow, 

 often almost cylindric. 

 Involucres glabrous, 5-7-flowered. 



Leaves lanceolate in outline, pumately lobed, with lanceolate to linear lobes. 



11. C. acuminata. 

 Leavesmoreorlesstwlcedissected,withllnear-flhformdivlsions. 12. C. sesilifolia. 

 Involucres canescent. 



Involucres cylindric; principal bracts of the involucres 5-8 (rarely 9-141; flowers 

 of the same number; bracts not black-hairy, except sometimes in C. gracilis. 

 Leaves not divided to near the midrib; blade proper wider than the lobes. 

 Blade proper broadly lanceolate; lobes usually directed downward. 



13. C. intermedia. 

 Blade proper narrowly lanceolate to almost linear; lobes curved upwards 

 or spreading. 14. C. angustata. 



Leaves dissected to near the midrib into Unear-flliform divisions, the blade 

 proper or rachis scarcely broader than the divisions. 15. C. gracilis. 

 Involucres campanulate; principal bracts of the involucres 9-18; flowers 10-20; 

 plant low. 

 Involucres and pedimcles without black hairs; achenes nearly columnar. 



16. C pumila. 

 Involucres and peduncles with some black hairs intermixed with the tomen- 

 tum; achenes more or less fusiform. 

 Hairs glandular. 17. C. occidentalis. 



Hairs not glandular. 



Achenes ribbed, at maturity brown or almost black. 



Stem low, 1-2 dm. high, as well as the petioles usually hispid with 



yellow hairs ; leaves not long-acuminate. IS. C. subacaulis. 



Stem tall, 4-5 dm. high, not hispid ; leaves long-acuminate. 



19. C. atribarba. 

 Achenes not ribbed at maturity, greenish or reddish. 20. C. scopulorum. 



21. HETEROPLEURA Schultz-Bip. l. h. Fcndleri. 



22. HIERACIUM (Tourn.) L. Hawkwebd. 



Involucres of the rather large heads irregularly more or less imbricate. 



Stem yellowish or whitish hirsute below. 1. H. columbianum. 



