ORDER 70. COMPOSITE. 161 



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

 ween tips, the outer spreading. Disk fls. tubular, 5 , ray fls. 2 , in one row, 

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

 simple, capillary. Cypsela compressed. 11 Very 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, 1,) 



B Scales destitute of green tip?, white or scarions. Lvs. never cordate. . .( 4-/>) 



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

 2. CALLIASTRUM. Heads corymbous or few, large. Kays 12 30, violet- 

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



a Lvs. ovate to lanceolate, serrate more or less. Pr. smoothish. . . .Nos. 35 



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



b bristly-fringed, pungent Nos. S, 9 



g J. ASTERIA. lids, panicled or rncemed, rarely few. Pap. equal, soft. ..(c) 



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



d entire or obscurely serrate. . .Nos. M -15 



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



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



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

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



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



/ Leaves ordinary (V 60. Scales with abrupt, appressed tips Nos. 20, 21 



e Scales loosely spreading. Lvs. entire Nos. 2225 



e Scales very loose. Lvs. long, serrate. . . .Nos. 2(i, 27 



ft Sca4es of the involucre closely imbricated (obtuse, No. 20), acute Nos. 2831 



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



k Pappus tawny-brown Nos. 35, 3K 



m Scales squarrous-spreading at the tips. o Hds. large (6"-!'), purple,. Nos. 37, 38 



o Hds. small (2-4"), whitish. .Nos 45-41 



m Scales loosely divergent, straight. Heads medium size, rays pale No. 4'J 



m Scales erect, straight, in 1 row. Heads 23, or solitary, rays white No. 48 



m Scales closely imbricated. n Hds. medium (3-ti"j. purp. or pale. . .Nos. -<3, 44, 31 



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



4. SCARIOSI. p Lvs. lanceolate, broadly or narrowly. Scales obtusish Nos. 40 51 



p Lvs. subnlaie or lin. Scales very acute. f Hds. large, few.. Nos.52, 53 



s Hds. small, many. . .54 5( 



1 A. corymboKU* Ait. Nearly smooth : Ivs. thin, ovate-acuminate, serrate, the puti 



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



2 A., macropli^llus Willd. Rough-pubescent ; leaves thickish, ovate, sen-ate will' 



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

 R A. mirabllls T. & G. Lvs. ovate, serrate, the lowest petiolate, the ramial round 



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

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



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



5 A . spectabilis Ait. Lvs. lance-oblong, sessile, entire, the lower subserrate ; tcvol 



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



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



heads 1 -5 ; scales linear-oblong, ciliate, inner obtuse. Wet. N. J. to Car. If. 

 0. srr<lrtlls. Heads 8 12, smaller; rays 12; scales but slightly spreading. 



7 A. pal'jidosus L, Slender, glabrous ; Ivs. long, linear : hds.l 6; scales lance linear 



rays 30. i- - i._ r er than the ((5") invol. Swamps. S. 2 3f. He ! irt' very large 



11 



