312 



f Plants 

 unarmed. 



1. 



LXXV. COMPOSITE. 



Pappus capillary. . 



Scales much imbricated. ( Pappus plumose. . 

 ^spreading, petaloid. . 

 , Scales in 2 series, . . I erect, greenish. . 



' Flowers all perfect. (.Scales in l row or series ~ 



l Receptacle $ Heads heterogamous. 



f Scales < not chaft'y. (. Heads dioecious, 

 colored. ( Receptacle chaffy 



t Fls. all t Invol. imbricated. . 

 < equal. ( Invol. calyculate. . 

 Scales ^ Herbs. ( Ray flowers larger, sterile. . 

 I Fls. not all perfect. I green. Shrubby. Heads dioecious. 



( Scales acute- 5 Achenia smooth 



f with spinose < cuspidate. . . ( Achenia rugose, 4-angled. 



J leaves ( Scales emarginate-mucronate 



Heads homogmous. 



.Plants armed. I with spinose heads only. (. Heads heterocephalous. 



Vernonia. 



Liatris. 



Hymenopappus. 



Elephantopus. 



Cacalia. 



Gnaphalium. 



Antennaria. 



Filag-o. 



Pluchea. 



Erechtites. 



Centaurea, 



Baccharis. 



Cirsium. 



Onopordon. 



Cynara. 



Lappa. 



Xanthium. 



Eupatorium. 



i Receptacle flat. 



< homogamous. { Receptacle conical. Conoclimum. 



$ Heads many, ( heterocephalus Ambrosia. 



( erect. {. Head solitary, terminal Sclerolepis. 



\ Stem herbaceous, (. climbing and twining Mikcmia. 



2. \ Stem shrubby. Heads monoecious . Iva. 



( Heads corymbose. . Tanacetum. 



$ erect. ( Heads racemose. . . Artemisia. 



C dry, (spreading, petaloid, yellow. . Xeranthemu/m. 



S green. . Senecio. 



$ erect, close, yellowish. Bigelovia. 



f Corollas Scales unarmed, (.herbaceous, (spreading and loose. . Carthamus. 



{Leaves < all equal. (Scales of the involucre doubly spinose Cnieus. 



alternate. ( Outer corollas enlarged and sterile Amberboa. 



J Awns of the achenia re trorsely hispid Bidens. 



Leaves opposite. { Awns of the achenia upwardly hispid Coreopsis. 



$ Heads small. Solidago. 

 f Involucre 

 I imbricated, 

 f flat or i Involuc. no 

 J convex. I imbricated. 



f Receptacle not chaffy, (.conical or globose. 



Pappus simple. ( Hds. ve 



Pappus double. Hds. midl. size. Chrysopsis. 



Inula. 



J 



Outer scales very short or 0. . Senecio. 



Outer scales equal to the inner. Calendula. 



Ray flowers pistillate. . . Helenium. 



Ray flowers neutral. . . Leptopoda, 



Achenia quadrangular. . Rtulbeckia. 



( Pappus minute or 0. { Achenia compressed. . Lepachys. 



( Rays \ Pappus of 2 caducous awns. Achenia wingless. Helianthus. 



< sterile. ( Pappus of 2 persistent awns. Achenia winged. Actinomeris. 

 Receptacle chafly. ( Rays fertile. Ach. obcompressed (parallel with the scales). Silphium. 



t Awns of ach. retrorsely hispid. Bidens. 



< Involucre double. \ Awns of ach. erectly hispid. . Coreopsis. 



{Rays sterile. \ Involucre imbricate in 3 or more rows. . . . Helianthus. 



$ Achenia obovoid, thick. . . Polymnia. 

 ( disk sterile. . . . I Achenia obcompressed, winged. Silphiwm. 



$ Receptacle nearly flat. . . Verbesina. 



Rays fertile, ( disk perfect. . . . ; Receptacle conical. . . . Heliopsis. 



J ^ Scales 5, united in 1 row. . Tagetes. 



pinnate. ^Sc. in 2 rows, outerrow distinct. Dysodia. 



$ Lvs. opposite, ( undivided. Scales distinct. . . . Arnica. 



5. I Recept. not chaffy. I Leaves radical, appearing after the solitary head. . . Tussilago. 



$ Rays white, shorter than scales. Eclipta. 



J Receptacle flat. (Rays rose color Coreopsis. 



$ simple. I Receptacle conical, with large paleae. . . . Zinnia. 



( Leaves opposite, (pinnately divided. Inner invol. of 8 united scales. . . Dahlia. 



\ Heads corymbose Nardosmia. 



(. Head solitary, heterog-amous Bellis. 



$ Achenia silky. Rays about 5. . Sericocarpus. 



'Pappus t copious. I Achenia smoothish. Rays 6100. Aster. 



iimple, { of 2 short bristles and several minute ones. Boltonia. 



$ Heads middle size. . . . Diplopappus. 



. Pappus double. { Heads very large. . . . Callistephus. 



', Pappus capillary. Invol. subsimpie. Rays 20200. Erigeron. 



6. ( Leaves all radical. 



f alveolate. 



f Receptacle J 

 not chafly, C smoothish. ( Pappus none. 



7. 



t Receptacle chaffy. L Leaves unc 



i& 



Involucre depressed, broad. 

 . I Involucre hemispherical. . 

 Rays pistillate. 

 5 Disk fls. yellow. \ Rays neutral. 

 fLvs. finely divided. ( Disk fls. white. Rays pistillate. 



$ 3 or 4. 



J Rays very short, white, 1 5. 

 divided. ( Rays very large, purple. . 



$ in 23 rows. 



J Scales of the invol. equal. ( in 1 row. 

 J Flowers yellow. ( Outer scales shortest, pappus capillary. 



Lvs. radical. ; Flowers white ; pappus plumose 



J Pappus single, bristly. 



J Lvs. unarmed. <Pap. double, outer scaly. Cynthia. 

 (Fls. yellow. ( Lvs. spinose-dentate ; pappus very white. Sonch.vs. 

 C Achenia^ Flowers blue. Pappus small, scaly. . . . Cichorium. 



not rost. ( Fls. whitish or cream color. Pap. copious, capillary. Nabalus. 

 C with a fili- $ Involucre with calyculate scales. . . Lactuca. 

 Achenia< form beak. I Involucre without calyculate scales. . Tragopos-on 

 Lvs. caulme. L rostrate. ( with a short, thick beak; involucre imbricate. . . Mulgedium. 



Leucanthemum. 



Chrysanthemum 



Anthemis. 



Maruta. 



Achillea. 



Verbesina. 



Partheninm. 



Echinacea. 



Troximon. 



Krigia. 



Taraxicum. 



Leontodon. 



Jlieracium. 



