THISTLE FAMILY 225 



Receptacle with chaffy paleae subtending the flowers. 



Tribe 6. HELIANTHEAE. 

 Receptacle naked, or in Gaillardia and in some species of Chaenactis 

 with bristles: but not chaffy bracted. 

 Plant-tissues without oil glands. Tribe 7. HBLBNIEAE. 

 Plant-tissues, especially the leaves and the bracts with oil-tubes; 

 plants therefore heavy-scented. Tribe 8. TAGETEAE. 

 Bracts of the involucres dry and scarious. Tribe 9. ANTHEMIDEAE. 

 Pappus capillary; style-branches often appendaged. 



Tribe 10. SENECIONEAE. 

 Anther-sacs caudate at the base; heads never radiate and corollas yellow only in a few 

 species of Cirsium. 

 Anthers not appendaged at the top; heads heterogamous or dioecious. 



Pistillate flowers with flUform corollas. Tribe 4. GNAPHALIEAE. 



Pistillate flowers with tubular-ampUate corollas. Tribe 5. ADENOCAULEAE. 

 Anther with elongated cartilaginous, mostly caudate appendages at the top; flowers 

 all hermaphrodite or the marginal neutral; corolla not flUform. 



Tribe 11. CYNAREAE. 



Tribe 1. VERNONIEAE. 

 One genus. 1. Vernonia. 



Tribe 2. EUPATORIEAE. 

 Achenes 5-angled without intervening ribs. 



Pappus double of 2-12 capillary bristles and as many or fewer outer shortthin scales. 



2. HOFFMBISTERIA. 



Pappus of wholly capillary bristles, mostly unlserial. 3. EUPATORIUM. 



Achenes 8-20-ribbed or 8-20-striate. 



Bracts of the involucre herbaceous or partly colored, not striate. 



6. Laciniaria. 

 Bracts of th^ involucres not herbaceous, striate-nerved. 



Pappus-bristles plumose; anthers distinct; bracts few. 5. KOHNIA. 



Pappus-bristles scabrous or barbellate; anthers imited; bracts usually many. 



4. COLEOSANTHUS. 

 Tribe 3. ASTEREAE. 

 A. Plants not dioecious. 



I. Marginal pistillate flowers, if present, ligulate. 

 a. Ray-flowers yellow or none. 



1. Pappus of scales or awns or lacking, never of numerous capillary bristles. 



a. Bracts not conspicuously scarious-margined. 



Heads small, not over 4 mm. high, few-flowered; pappus more or less 

 paleaceous. 

 Disk-flowers usually fertile; leaves linear to flliform. 



7. GUTIERREZIA. 



Disk-flowers sterile; leaves short, obovate or spatulate. 



8. Amphipappus. 

 Heads large, many-flowered; involucre in all except one species viscid. 



Involucres hemispherical; pappus of a few deciduous awns. 



9. Grindelia. 

 Involucres turbinate; pappus of persistent linear, very acute paleae. 



10. Vanclevea. 



b. Bracts with conspicuous scarious flmbriate margins. 



•11. ACAMPTOPAPPUS. 



2. Pappus at least in part of numerous capillary bristles. 



o. Pappus double, the inner of capillary bristles, the outer of paleae or 

 short bristles; involucres many-flowered, hemispherical with narrow 

 imbricated bracts. 12. Chrtsop3I3. 



6. Pappus wholly of capillary bristles. 

 Heads discoid. 



Leaves resinous-pimctate. 13. Ericambria. 



Leaves not resinous-pimctate. 



Involucres narrowly turbinate, its bracts more or less charta- 

 ceous, keeled, arranged in definite (usually 5) vertical ranks; 

 achenes elongate-linear; tips of style-branches subulate-fili- 

 form. 14. Chrysothamnos. 

 Involucres broadly turbinate to hemispheric, its bracts more or 

 less imbricate, but not in definite vertical ranks ; achenes 

 scarcely elongate-linear. 

 Style-tips obtuse; involucral bracts narrow and poorly im- 

 bricate. (Rayless species of) 45. Erigeron. 

 Style-tips acute; bracts either broad or well imbricate or 

 both. 

 Achenes truncate at the top, gradually tapering towards 

 the base, usually cinereous-pubescent ; bracts neither 

 broad nor abruptly acuminate. 

 Appendages or tips of the style-branches flliform; 

 undershrubs with white-tomentulose stems and 

 glandular-hairy foliage; leaves entire-margined. 

 21. Macronema. 

 Appendages or tips of the style-branches subulate to 

 ovate. 

 Leaves with spinulose-tipped teeth; corolla-tube 

 slender. (Rayless species of) 



17. SrOBRANTHUS. 



