43 6 



COMPOSITAE. 



VOL. III. 



A genus of 130 species or more, of wide geographic distribution, most abundant in the New 

 World. In addition to the following, many others occur in the southern and western parts of North 

 America. Type species : Erigcron acris L. 



* Rays long, narrow, usually equalling or longer than the diameter of the disk. 

 t Stem i'-io' high, simple, leafy ; head solitary ; involucre woolly. i. . uniflorus. 



tt Stem 4'~3 high, leafy, usually branched ; involucre hirsute or glabrous. 



I. Roots perennial, thick and woody. 



Heads i'-a' broad; leaves lanceolate, ovate, oblong, or spatulate. 

 Rays violet or purple ; stem leaves ovate, lanceolate, or oblong. 



Stem leaves linear-lanceolate, the upper much smaller. 2. E. asper. 



Stem leaves ovate-lanceolate, the upper little smaller. 3. E. subtrinervis. 



Rays mostly white ; stem leaves linear or linear-oblong. 4. E. caespitosus. 



Heads l / 2 '-i' broad; leaves linear. 



Plants hirsute or canescent ; pappus double ; western species. 

 Stem hirsute ; achenes pubescent ; flowers white. 



Stem appressed-canescent ; achenes glabrous ; flowers purple or white. 

 Plant nearly glabrous ; pappus simple ; northern. 



2. Perennial by decumbent, rooting stems or stolons. 



3. Roots annual or biennial, fibrous ; plants often perennial by offsets. 



5. E. pumilus. 



6. E. canus. 



7. E. hyssopifolius. 

 E. ft age liar is. 



9. E. pulchellus. 



10. E. philadelphicus. 

 n. E. diver gens. 



12. E. Bellidiastrum. 



E. annuus. 

 E. ramosus. 

 E. tenuis. 



Heads i'-ij4' broad, few; stem simple; eastern. 

 Heads j4'-i' broad, numerous ; stem branched. 

 Rays 100-150, narrow, mostly purple or violet. 



Pappus simple ; plant erect, corymbosely branched. 

 Pappus double ; plant diffusely branched, western. 

 Rays much less numerous, purplish or white. 



Plants 6'-i2' high, diffuse, western; pappus simple. 

 Plants 6'-3 high, erect, branched; pappus double. 

 Pappus of the ray-flowers and disk-flowers unlike. 

 Stem leaves lanceolate, nearly all sharply serrate. 

 Stem leaves linear-lanceolate or oblong, nearly all entire. 

 Pappus of the ray-flowers and disk-flowers alike ; plant hirsute. 



ttt Stem leafless or nearly so ; heads J^' broad, corymbose. 16. E.vernus. 

 ** Rays inconspicuous or short; a row of tubular pistillate flowers inside the row of rays. 



17. E. acris. 



i. Erigeron uniflorus L. Arctic Erigeron. Fig. 4361. 



Erigeron uniflorus L. Sp. PI. 864. 1753. 



Perennial by short branching rootstocks; stems slender, 

 single or .tufted, more or less pubescent, simple, erect, i'-io' 

 high. Basal leaves petioled, spatulate, obtuse, entire, i'-2 r 

 long; stem leaves sessile, lanceolate or linear-lanceolate, en- 

 tire, acute or obtuse; head solitary, peduncled, i'-i' broad; 

 rays about 100, purple or purplish, 2" -4" long; involucre 

 hemispheric, its bracts linear-lanceolate, acute, copiously 

 woolly; pappus simple. 



Labrador and Arctic America to Alaska, south in the Rocky 

 Mountains to Colorado and in the Sierra Nevada to California. 

 Also in Europe. Summer. 



2. Erigeron asper Nutt. Rough Erigeron. 

 Fig. 4362. 



Erigeron asper Nutt. Gen. 2: 147. 1818. 

 Erigeron glabellus Nutt. loc. cit. 1818. 



Perennial by a woody root; stem simple, or 

 branched ^above, more or less pubescent, sometimes 

 hirsute, 6'-24' high. Leaves glabrous, pubescent or 

 ciliate, ^entire, the basal ones spatulate, obtuse, 2'-^ 

 long, 3"-i' wide, narrowed into margined petioles; 

 stem leaves oblong-lanceolate or linear-lanceolate, 

 obtuse or acute, the upper smaller; heads several or 

 solitary, slender-peduncled, i'-2' broad; involucre 

 hemispheric, its bracts linear, acute, hirsute or pu- 

 bescent; rays 100-150, very narrow, violet, purple, 

 or nearly white, 4"~7" long; pappus double, the 

 outer row of bristles much shorter than the inner. 



In dry soil, Minnesota to Wisconsin, Nebraska, Manitoba, Utah and New Mexico, 

 differ in pubescence. June-Sept. 



Races 



