250 COMPOSITAE. 



372. CREPIS. 



Annual, biennial or perennial plants with milky juice; heads 

 several-many-flowered ; flowers yellow ; involucre usually double ; 

 receptacle flat, naked, sometimes alveolate; pappus simple, of 

 copious and white capillary bristles which are not plumose; 

 corollas all ligulate; akenes oblong, linear or fusiform, nearly 

 terete or obtusely angled, 10-20-ribbed, generally contracted at 

 base and more tapering at the apex, sometimes even beaked. 



Involucral bracts bearing soft bristles. C. barbigera. 

 Involucral bracts not bearing soft bristles. 



Heads 5-10-flowered; stems tall, slender. C. gracilis. 



Heads 25-30-flowered; stems stout, low. C. occidentalis. 



Crepis barbigera Leiberg. Perennial, erect, 40-50 cm. high, minutely 

 viscid-pubescent; basal leaves oblong-lanceolate, 15-30 cm. long, attenuate- 

 acute, pinna tely toothed, lobed or parted; cauline similar, smaller; heads in a 

 loose cyme; involucre 10-15 mm. long; bracts linear-oblong, acutish, strongly 

 carinate and armed with one or two rows of stout soft usually pale bristles; 

 akenes 8-10 mm. long, olive green, 10 or 12 ribbed; pappus copious, shorter 

 than the akene. In rocky or gravelly soil. C. atrabarba Heller is a form of 

 this species or perhaps distinct, from Lake Waha. It has smaller heads with 

 fewer flowers and short black bristles on the involucre. Its true relationship 

 may be with C. gracilis but only immature plants are known. 



Crepis gracilis (D. C. Eaton) Rydb. Perennial, erect, thinly canescent 

 or glabrate, 30-60 cm. high; leaves lanceolate, attenuate-acuminate, with few 

 or numerous slender teeth or lobes, or divided into narrow segments, rarely 

 entire, 10-20 cm. long, the basal ones petioled; heads 5-10-flowered, loosely 

 or somewhat compactly corymbose; involucre oblong-cylindric, ashy-pu- 

 berulent, the principal bracts 5-9 in number, 10-12 mm. long, with a few small 

 ones at base; akenes acutely 10-ribbed when mature, oblong-fusiform, attenu- 

 ate toward the apex, a little longer than the bright white soft pappus. Rather 

 common, very variable. 



Crepis occidentalis Nutt. Perennial, erect, thinly white-tomentose through- 

 out, 8-30 cm. high; stems usually with few erect branches; leaves broadly 

 lanceolate, acute or acuminate, 5-10 cm. long, pinnately toothed or cleft into 

 narrow lobes, short-petioled or sessile; heads on stout peduncles; involucre 

 oblong-cylindric, 12-18 mm. long, tomentose and with a few large black glan- 

 dular hairs, the principal bracts lanceolate, acuminate, the smaller basal bracts 

 relatively broader; flowers 25-30; akenes brownish, fusiform, 8-10 mm. long, 

 10-18-ribbed, longer than the bright white pappus. In loose rocks, not 

 common. 



373. HTERACIUM. HAWKWEED. 



Hispid and hirsute often glandular perennials with milky juice; 

 leaves merely toothed or entire; heads small to medium, panicu- 

 late or rarely solitary ; flowers yellow or sometimes white ; bracts 

 of involucre in two rows; receptacle flat, naked; pappus of a 

 single row of rough tawny bristles which are not plumose; 

 corollas all ligulate ; akenes oblong or columnar-, terete or 4- or 5- 

 angled, mostly 10-ribbed or striate, the apex truncate. 



