CJCH OKI A CEA E. 903 



8. Crepis occidentals Nutt. Large-flowered Gray Hawksbeard. 

 (I. F. f. 3560.) Perennial, scurfy and canescent, sometimes also hirsute; stem 

 ratlier stout, leafy, branched, 15 45 high. Leaves oblong-lanceolate or oblong in 

 outline, laciniate-pinnatifld. acute or acuminate, the lower and basal ones 15-25 cm. 

 lung, 1. arrowed into petioles, the upper sessile and slightly clasping; heads few or 

 several, corymbose, stout-peduncled, about 25 mm. broad; involucre oblong-cam- 

 panulate, canescent, its principal bracts 9-24, linear, acute; achenes oblong. 

 sharply 10-ribbed, glabrous. Plains, western Neb. (according to Gray) and Colo. 

 to Cal., north to the N. W. Terr, and Ur. Col. May-July. 



ax. HIERACIUM L. 



Perennial hispid scabrous glandular or glabrous herbs, with alternate or basal 

 i aves, and small middle sized or large, solitary corymbose or paniculate heads of 

 ) ellow orange or red flowers. Involucre cylindric, campanulate, or nearly hemis- 

 pheric, its principal bracts in 1-3 series, the outer either regularly and gradually 

 -mailer or abruptly much smaller, none of them much thickened at the base after 

 flowering. Receptacle flat, naked or short-fimbrillate. Rays truncate and 5-toothed 

 at the apex. Anthers sagittate at the base. Style-branches slender. Achenes 

 oblong, columnar, or fusiform, not beaked, 10- 15-ribbed, terete or 4-5-angled. 

 Pappus copious, or 1-2 rows of simple rather stiff persistent brown or brownish 

 bristles. [Greek, hawk.] Not fewer than 300 species, natives of the north tem- 

 perate zone and the Andes of S. Am. Besides the following, some 15 others occur 

 in western N. Am. 



* Flowering stem leafless, or with 1-5 leaves; achenes columnar or oblong, truncate, 

 (a) Stem scapose, with a single head only; introduced; principal bracts in 1 or 2 series. 



1. H. Pilose II a. 

 (b) Heads corymbose or paniculate ; principal bracts in 1-3 series. 

 Leaves coarsely dentate; introduced species. 



Leaves cordate or subcordate. 2. H. murorum. 



Leaves narrowed at both ends. 3. //. vulgatum. 



Leaves denticulate or entire. 



Leaves mostly entire, spatulate to oblong; heads corymbose; introduced species; 

 principal bracts of the involucre in 2-3 series. 



Heads 16-25 mm. broad ; flowers red or orange. 4. H. aurantiacum. 



Heads 10-18 mm. broad ; flowers yellow. 



Glaucous, slightly hispid. 5. H. praealtum. 



Densely hirsute. 6. H. pratense. 



Leaves, at least some of them, denticulate, mostly obovate or oval; heads corymbose- 

 paniculate; natives; principal bracts in x series. 



Principal bracts of the involucre glabrous, or nearly so. 



Stem glabrous, or nearly so : leaves usually purple-veined. 



7. H. venosum. 

 Stem pilose below ; leaves green. 8. H. Marianum. 



Involucre and peduncles densely hirsute and glandular. 9. H. Greenii. 

 * * Flowering stem abundantly leafy, at least below, 

 (a) Principal bracts of the involucre in 2-4 series; heads corymbose. 

 Leaves sessile, not clasping; involucre glabrous. 10. 11. umbellatum. 



Leaves, at least the upper, clasping: involucre pubescent. 11. H. Ca71aden.se. 



(b) Principal bracts in 1 series; heads small, paniculate or racemose. 

 I. Achenes columnar at maturity, truncate. 

 P. ant nearly or quite glabrous except towards the base; heads 15-20-flowered. 



12. H. paniculatum. 

 Plants scabrous or glandular; heads 15-50-flowered. 



Peduncles stout, spreading. 13. H. scabrum. 



Peduncles slender, ascending. 



No tuft of basal leaves at flowering time. 8, H. Marianum. 



Basal leaves present at flowering time. 14. H. Alleghaiiiense. 



2. Achenes spindle-shaped, or with a tapering summit at maturity. 

 Leaves and lower part of the stem pilose. 15. H. Gronovii. 



Leaves and stem densely clothed with very long brown hairs. 16. H. longipilum. 



1. Hieracium Pilose'lla L. Mouse-ear Hawkweed. (I. F. f. 3561.) Sto- 

 loniferous. pilose-pubescent throughout; stolons leafy, rooting, slender, 7-30 cm. 

 long. Scape slender, erect, 10-25 cm. high, leafless, with a single head; leaves 

 •blong or spatulate, entire, obtuse or acutish at the apex, narrowed into petioles, 



