ASTER 257 



(y) Heads fewer in a narrow spike-like 



cluster 



m. Stems and involucres white- felted A. Wrightii 

 n. Stems and involucres hairy to 



smooth A. boredlis 



ASTER Linne 1753 ASTER 



(Gr. aster, star) 



PL 38, fig. 5. 



Heads with white, pink, blue, violet or purple pistillate ray-flowers, 

 disk-flowers yellow, becoming brown, purple or red, perfect, achenes usu- 

 ally flattened and nerved, pappus of hair-like bristles ; receptacle flat to 

 convex, without chaff, involucre hemispheric to top-shaped, the bracts usu- 

 ally unequal and imbricated in several rows, sometimes about equal and 

 in 2-3 rows; heads solitary or in corymbs or panicles; leaves alternate, 

 simple; perennial or rarely annual. 



1. Annuals 



a. Bracts linear or linear-lanceolate, pointed A. angustus 



b. Bracts oblong to oblanceolate, blunt or rounded A. frondosus 



2. Perennials 



a. Bracts spiny-pointed; stems tufted, 1-headed 



(1) Leaves not spiny-toothed, spatulate or 



oblanceolate; heads 10-15 mm. wide; 



rays white A.villosus 



(2) Leaves spiny-toothed, spatulate; heads 10- 



12 mm. high ; rays purple A. color adensis 



b. Bracts not spiny-pointed 



(1) Bracts broad with keel-like midrib, papery, 



usually fringed and purple-tipped 



(a) Involucres 12-20 mm. wide; leaves 



mostly 1.5-2.5 cm. wide A. Engelmdnnii 



(b) Involucres 6-10 mm. wide; leaves usu- 



ally less than 1 cm. wide 

 x. Stems usually simple; bracts purple, 



acute A. elegans 



y. Stems usually much branched; bracts 



scarcely purple, outer rounded or 



blunt A. glaiicus 



(2) Bracts mostly narrow, without keel-like 



midrib 



