Order 70.— ASTERWORTS. 



235 



g Ach. with a long beak, pap. silk- wliite. Heads erect, c. JVi I'/ Lettuce. Lactv'cx 

 g Acheuiu not beaked, pappus diiU-wiiite., lid.-. ikkI. c. I)rQp-flow<r. N.\b'alus 10 

 g Aehenia not lieaked, i)ap. duU-wiii'e; Jlds. erect, piu'i le. S. r. Lyoode.s'.mkv 



521 523 519 520 51S vfl 



Achenia of Asterworts. showins: the varying pappus. Fig. 518. Acheninin <if Eclipta, r,o, 

 pappus. Fig. 519. Horseweed {Ambrosia trijid a). Fig. 520. Sunflower; pappus 2 teeth 

 Fig. 521. Ageratum,— 5 scales. Fig. 522. Blue Lettuce,— many hair-like bristles. Fig. 523. Wllcl 

 Lettuce, pappus raised on a beak. 



1. SOLID A'GO. Goldenrod. 

 Heads few-flowered, tlie rays 1-15, pistillate, disk florets perfect. In- 

 volucre oblong, imbricate, with close-pressed scales. Receptacle alveo- 

 late, narrow. Pappus simple, of equal, hair-like, rougli bristles. — Herbs, 

 very abundant in the United States. Stem erect, branching near the top. 

 Leaves alternate. Heads small, florets all yellow (in S. bicolor, whitish), 

 opening from August to October. (See Figs. 501-503.) 



IF Shrub woody, l-3f, high. Heads with 1-3 rays. S 1 



H Herbs. Heads without rays (discoid). S 2,3 



^ Herbs. Heads witli rays (1-15, generally small) a 



a Scales of the involucre with recurved, leafy, green tips. . . .4, 5 

 a Scales of the involucre erect, tips scarcely at all green.... b 

 b Heads (white or yellow) in axillary, close clusters or short racemes. . . .6-9 



b Heads in terminal racemes forming a close or a spreading panicle c 



b Heads in terminal compound corymbs n 



c Racemes erect, not one-sided. Leaves feather-veined.. . .d 

 c Racemes spreading or recurved, the flowers all on one side. . . .f 

 d Alpine species (growing only on moimtains). Heads quite large 10-12 



d Not alpine — growing in plains or low grounds. Heads not large . . 

 e Plants very smooth, at least the stem and leaves. Rays 4-7. . , 

 e Plants downy or hoary with very close soft hairs. Rays 9-12. 



t Lraves ^ or 1-veined. Very smooth salt-marsh \ erbs 18, 19 



f Leaves evidently 3-veined. Herbs inland, &c. . , .g 



f Leaves not veiny, thick, subcutive 27-29 



f Leaves evidently feather-veined, mostly serrate ..k 



.0. 



.13-15 

 ...16,17 



