82 KEY TO THE SPECIES 



2. Taraxacum. Scape hollow, achene 4-5 angled, spinulose at summit, with 

 very long slender beak. 



+- -J- Stems usually leafy ; heads paniculate or corymbose. 



3. Crepis. Leaves entire to pinnatifid ; achenes narrowed at summit but not 

 beaked. 



* * Flowers blue. 



4. Lactuca. Stems leafy ; achenes flattened, nerved and short-beaked. 



1. AGOSERIS 



Acaulescent herbs with rosulate nearly sessile leaves, naked scape, imbricated 

 involucre of unequal bracts, flat receptacle, truncate 5-toothed rays, slender style- 

 branches, and a copious pappus of slender white bristles. 



1. Ag:oseris glauca (Pursh) Greene (Large-flowered Agoseris). Glabrous 

 and somewhat glaucous ; leaves from oblong-lanceolate to nearly linear, entire to 

 somewhat pinnatifid ; scape longer than the leaves, 1-iJ dm.. high : involucre cam- 

 pauulate, its bracts lanceolate, glabrous, 3-4 cm. broad ; the achene with its stout 

 nerved beak 10-12 mm. long, longer than the scabrous pappus. Moist slopes and 

 valleys. 



2. Agoseris Leontodon Rydb. (Cut-leaved Agoseris). Cinerous-pubescent, 

 especially while young, somewhat tufted ; stems slender, ascending, 5-12 cm. long ; 

 leaves lanceolate in outhne, more or less laciniate-pinnatifid ; bracts of the involucre 

 lanceolate; heads only 2-3 cm. broad; the rays usually purplish externally. Moist 

 valleys. 



2. TARAXACUM (Dandelion) 



Herbs with basal rosette of pinnatifid leaves, large and solitary heads on slen- 

 der hollow stems, double involucre (outer short scales, inner long and narrow erect 

 scales in a single row), and an oblong ribbed achene prolonged into a very slender 

 beak bearing the soft white pappus. 



1. Taraxacum Taraxacum (L.) Karst. Smooth or at first hairy ; outer 

 involucre reflexed ; inner involucre at first erect, but reflexed in fruit and 

 exposing the globular head of pappus. Everywhere. From Europe. (See Plant 

 Relations, p. 114, Fig. 113 ; also Plant Structures, p. 213, Fig. 187 ; p. 277, Fig. 262 ; 

 p. 278, Fig. 263.) 



3, CREPIS (Hawksbeard) 



Perennials with sparsely leafy stems, often branching, entire or pinnatifid 

 leaves, yellow flowers, soft white pappus, striate achenes narrowed at summit (not 

 beaked). 



1. Crepis glauca (Nutt.) T. & G. Glabrous and somewhat glaucous, stems 

 nearly or quite leafless, ascending, 2-4 dm. long ; leaves basal from entire to 

 laciniate-pinnatifld, broadly spatulate to lanceolate ] heads few-several, about 2 

 cm. broad, on long slender peduncles ; bracts of the involucre lanceolate, acute 

 except the outer very short ovate ones ; achene f usiform-cylindric, with 10 well- 

 marked ribs. Moist alkaline soil. 



2. Crepis acuminata Nutt. Somewhat cinerous-pubescent ; stems l-several 

 from the crown, 3-5 dm. high ; leaves large, petioled, oblong-lanceolate in outline, 

 deeply and irregularly pinnatifid, long acuminate at apex ; heads small, very 

 numerous in a corymbose-cyme ; involucre glabrous, few-flowered (4-6), its bracts 

 somewhat keeled or thickened at base ; achenes fusiform, longer than the pappus. 

 Frequent on dry stony hills. 



