268 COMPOSITAE. 



Erigeron philadelphicus L. Perennial, sparsely hairy ; stems erect, branched 

 above, 30-90 cm. high; basal leaves oblong or oblong-obovate, obtuse, dentate, 

 3-6 cm. long, narrowed into a short petiole; cauline mostly entire, sessile and 

 half-clasping; heads numerous in a cyme; involucre hemispheric; rays pink, 

 numerous, very narrow; akenes puberulent. Moist banks and meadows. 



Erigeron fllifolius (Hook.) Nutt. (£. peucephyllus Gray.) Perennial, 

 green or slightly canescent, the pubescence minute and appressed; stems 10-30 

 cm. high, erect, little branched; leaves linear or slightly dilated at tip, 2-5 

 cm. long; involucre 6-8 mm. high, hirsute, bracts unequal; rays 20-40, golden 

 yellow, about 1 cm. long; pappus double. In thin rocky soil. 



Erigeron compositus Pursh. Pernnial, tufted from a woody crown; 

 leaves hirsute or glabrous; basal leaves long-petioled, the blade 1-3-times 

 ternately divided into linear obtuse lobes, 4-10 mm. long; cauline sessile, 

 mostly linear and entire; flowering stems 6-15 cm. high, bearing solitary heads; 

 rays 30-50, pink or white, 6-10 mm. long; akenes short-pubescent; pappus 

 simple. In sandy soil. 



Erigeron poliospermus Gray. Perennial, in dense tufts, sparsely hispid 

 throughout; stems numerous, simple, 2-10 cm. high, each bearing a single 

 head; leaves spatulate, obtuse, the petioles slender; involucre densely hairy, 

 the bracts narrow; rays 20-30, violet or white, rather broad; akenes white 

 hairy; pappus double. In dry soil, most common in the sagebrush region. 



Erigeron hispidissimus (Hook.). Piper (£. concinnus T. & G.). Perennial, 

 erect, commonly tufted from a stout crown, 10-30 cm. high, very pubescent, 

 with long and soft hairs; leaves spatulate-linear, entire, 2-8 cm. long, nearly 

 erect; heads loosely corymbed; involucre hirsute, 5 mm. high; rays white, 

 pink or violet, numerous, 5-6 mm. long; pappus double, the outer short but 

 conspicuous. Dry ground, common about Spokane. 



Erigeron corymbosus Nutt. Perennial, tufted, erect or decumbent, 15-50 

 cm. high, harshly pubescent throughout; radical leaves linear-lanceolate, 

 spatulate, 3-nerved, 6—15 cm. long; cauline linear, 1-nerved, acuminate, sessile, 

 gradually smaller to the top; heads slender-peduncled, sometimes solitary, 

 mostly in loose corymbs; involucre 7-8 mm. high, whitish, hirsute; rays 30-50, 

 violet, rarely white, 6-12 mm. long; pappus double, the outer bristles very short, 

 sometimes wanting. Common on grassy prairies. 



Erigeron linearis (Hook.) Piper. Perennial, the caudex woody, branched; 

 pubescence whitish, fine and appressed; stems 15-50 cm. high, loosely branched 

 above and bearing few to many heads; leaves linear or slightly dilated at tip, 

 firm, 2-5 cm. long; involucre 4-5 mm. high, the bracts subequal, appressed- 

 pubescent; rays pink to violet, 6-8 mm. long; pappus simple. In gravelly soil, 

 usually abundant where sagebrush occurs. 



402. ASTER. 



Mostly perennial herbs; leaves alternate; heads solitary, 

 corymbed or panicled, many-flowered, radiate; ray-flowers sev- 

 eral or numerous, in one row, fertile or rarely sterile, white, 

 purple or blue, never yellow; disk-flowers yellow, often turning 

 purple; involucre imbricated ; bracts commonly with herbaceous 

 tips; receptacle flat or convex, naked; pappus tawny, simple, of 

 copious slender scabrous capillary bristles; anthers tipped with 

 an appendage; styles appendaged; akenes more or less com- 

 pressed, rarely slender, 4^5-nerved. 



