ORDER 70. COMPOSITE. 161 



18, ASTER, L. Invol. oblong, imbricate. Scales loose, often with 

 green tips, the outer spreading. Disk fls. tubular, , ray fls. $ , in one row, 

 ligulate, 3-toothed at apex, finally revolute. Recep. flat, alveolate. Pap. 

 simple, capillary. Cypsela compressed, u Veiy abundant in the U. S., 

 flowering in late summer and autumn. Lvs. alternate, diminishing grad- 

 ually upward. Disk-flowers yellow, changing to purple ; ray-flowers blue, 

 purple, or white, never yellow. Figs. 146, 388. (See also p. 446.) 



A Scales of the invo.ucre tipped with green or wholly green. . .( 1, 2, 3) 



B Scales' destitute of green tips, white or scarious. Lvs. never cordate. . .( 4-/?) 



1. BIOTIA. Heads corymbous, large. Rays 6 15, white. Lvs. cordate Nos. 1, 2 



5 2. CALLIASTRUM. Heads corymbous or few, large. Rays 1230, violet- 

 blue. Pap. bristles unequally thickened. Lvs. rigid, not cordate (a) 



a Lvs. ovate to lanceolate, serrate more or less. Fr. smoothish Nos. 3 5 



a Leaves lance-linear to linear, b entire, merely acute Nos. 6, 7 



b bristly-fringed, pur.gent Nos. S, 9 



| J. ASTERIA. Hds. panicled or racemed, rarely few. Pap. equal, soft...(c) 



c Leaves petiolate, the lower cordate, d evidently serrate Nos. 10, 11 



d entire or obscurely serrate. . .Nos. 1215 



c Leaves all sessile, entire, silky-canescent both sides. Pap. tawny Nos. 16, 17 



c Lvs. not silky, d clasping with a cordate or auriculate base. . .(/) 



d clasping with a broad base not cord, or auric. . .(h) 

 d sessile with a narrow base, not clasping. . .(m) 



f Lv?. very small (!" 3"), entire. Scales with spreading tips Nos. 18, 19 



f Leaves ordinary (!' 6')- 6 Scales with abrupt, appressed tips Nos. 20, 21 



e Scales loosely spreading. Lvs. entire Nos. 2225 



e Scales very loose. Lvs. long, serrate Nos. 20, 27 



h Scales of the involucre closely imbricated (obtuse, No. 20), acute Nos. 28 31 



h Scales loose, or spreading, or recurved. k Pappus bright-colored. . .Nos. 32--34 



k Pappus tawny-brown Nos. 35, S6 



m Scales squarrous-spreading at the tips. o lids, large (6"-10, purple. .Nos. 37, 33 



o Hds. small (2-4 // ),whitisli..Nos.45-47 



m Scales loosely divergent, straight. Heads medium size, rays pale No. 43 



m Scales erect, straight, in 1 row. Heads 23, or solitary, rays white No. 43 



m Scales closely imbricated. n Hds. medium (3-6"), purp. or pale. . .Nos. 43, 44, 31 



n Heads small (2 3"), white or pale Nos. 3941 



4. SCARIEST. p Lvs. lanceolate, broadly or narrowly. Scales obtusish Nos. 49 51 



p Lvs. subulate or lin. Scales very acute. s Hds. large, few. .Nos. 52, 53 



s Hds. small, many. . .54 5 



1 A. coryinbosus Ait. Nearly smooth ; Ivs. thin, ovate-acuminate, serrate, the peti- 



oles wingless ; rays 6 9. Dry woods, N., M. 1 2f. Heads oblong, 4". Lvs. large. 



2 A. macropli^llus Willd. Rough-pubescent ; leaves thickish, ovate, serrate with 



close teeth, petioles some winged ; rays 8-15. Woods, N. l-2f. Lvs. very large. Hds. 6". 



3 A. mirabilis T. & G. Lvs. ovate, serrate, the lowest petiolate, the ramial round- 



ish ; invol. hemispherical, scales obtuse ; rays about 20. S. Car. Very rare. 



4 A. radula Ait. Lvs. lanceolate, acuminate, sessile, sharp-serrate, rough and rugous, 



invol. p quarrous with the spreading scale-tips ; rays 20. N. 1 3f. 



5 A . spectabilis Ait. Lvs. lance-oblong, sessile, entire, the lower suhserrate ; inrol 



hemispherical, scales linear-spatulate, ciliate. Sands, Mass, to Fla. 1 2f. 



6 A. surculosus MX. Root a creeping, knotted rhizome ; Ivs. lance-lineai and linear . 



heads 15 ; scales linear-oblong, ciliate, inner obtuse. Wet. N. J. to Car. If. 

 ft. g-rdclll*. Heads S 12, smaller; rays 12; scales but slightly spreading. 



7 A. palndosus L. Slender, glabrous; Ivs. long, linear : hds. 1 6; scales lance linear 



rays 30, longer than the (6") invol. Swamps, S. 2 3f. Bends very large 



Jl 



