Genus 35.] 



THISTLE FAMILY. 



385 



appendages short, mostly rounded or obtuse. Achenes flattened, usually 2-nerved. Pappus- 

 bristles fragile, slender, scabrous or denticulate, in 1 series, or often an additional outer 

 shorter series. [Greek, early-old, alluding to the early hoary pappus.] 



A genus of some 130 species, of wide geographic distribution, most abundant in the New World. 

 In addition to the following, about 60 others occur in the southern and western parts of North 

 America. 



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



t Stem i'-io' high, simple, leafy; head solitary; involucre woolly. 1. E. uniflorus. 



t t Stem 4'~3 high, leafy, usually branched; involucre hirsute or glabrous. 



I . Roots perennial, thick and woody. 



Heads 1/-2' 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. 



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



Rays mostl y white; stem-leaves linear or linear-oblong. 4. 



Heads J&'-i' broad; leaves linear. 



Plants hirsute or canescent; pappus double; western species. 



Stem hirsute; achenes pubescent; flowers white. 5. E. pumilis. 



Stem appressed-canescent; achenes glabrous; flowers purple or white. 6. E. canus. 

 Plant nearly glabrous; pappus simple; northern. 7. E. hyssopifolius. 



2. Perennial by decumbent rooting stems or stolons. 8. E. flagellaris. 

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



E. asper. 



E. subtrinervis. 



E. caespitosus. 



9. E. ptdchellus. 



10. 

 11. 



E. Philadeiphicus. 

 E. divergens. 



12. E. Bellidiastrum. 



-X- 



13^ 

 14, 



15- 



E. annuus. 

 E. ramosus. 

 E. vernus. 



Heads i'-i l A' broad, few; stem simple; eastern 

 Heads %'-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 i-3 high, erect, corymbosely branched; pappus double 

 Stem-leaves lanceolate, nearly all sharply serrate. 

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

 t t t Stem leafless or nearty so; heads %' broad, corymbose. 



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



16. E. acris. 



i. Erigeron uniflorus L. Arctic Erigeron. 

 (Fig. 381 1.) 



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, l / -2 / 

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

 tire, acute or obtuse; head solitary, peduncled, % f -\' 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. Also in Europe. 

 Summer. 



2. Erigeron asper Nutt. Rough 

 Erigeron. (Fig. 3812.) 



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

 Erigeron glabellas 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 / -4 / 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 pubescent; rays 100-150, very 

 narrow, violet, purple, or nearly white, \ ,f - r ]' f 



long; pappus double, the outer row of bristles much shorter than the inner. 



In dry soil, Minnesota to Nebraska, west to the Northwest Territory, Utah and New Mexico. 



June-Sept. 25 



