914 FLORA. 



* * * Anthers not tailed at the base; stigmatic lines of the style-branches in the per- 



fect flowers extending to the summit; flowers tubular only, or tubular 

 and radiate, often yellow. 



1. Receptacle naked (see also Nos. 79, 80, 81 and 82 of Tribe 7.) 



a. Bracts of the involucre usually well imbricated. 

 Style-branches of the perfect flowers flattened, with terminal appendages. 



Tribe 3. ASTEREAE. 



Style-branches truncate, or with hairy tips. Tribe 6. HELENIEAE. 



b. Bracts little imbricated, or not at all ; pappus of soft bristles. 



Tribe 8. SENECIONEAE. 



2. Receptacle chaffy (except in Nos. 79, 80, 81 and 82). 



Bracts of the involucre herbaceous or foliaceous; not scarious. Tribe 5. HELIANTHEAE. 

 Bracts of the involucre dry, scarious. Tribe 7. ANTHEMIDEAE. 



* * * * Anthers long-tailed at the base, with elongated appendages at the tip; heads 



large; rays none. (In Centaurea. often with enlarged marginal flowers; 



bracts imbricated. Tribe 9. CYNAREAE. 



Tribe i. VERNONIEAE. 



Pappus double, the inner of rough capillary bristles, the outer of scales, or short bristles ; 



heads not glomerate. i. Vernonia. 



Pappus a single series of bristles; heads glomerate, subtended by sessile bracts. 



2. Elephantopus. 



Tribe 2. EUPATORIEAE. 



* Achenes 3~5-angled, not ribbed. 

 Pappus of 5 broad obtuse scales; aquatic herb with linear whorled leaves. 



3. Sclerolepis. 

 Pappus of numerous capillary bristles. 



Involucre of more than 4 bracts; erect herbs. 4. Eupatorium. 



Involucre of 4 bracts; twining herbaceous vines. 5. Willugbaeya. 



* * Achenes 8-io-ribbed, or 8-io-striate. 



i. Bracts of the involucre in several series, the outer successively shorter. 

 Bracts of the involucre strongly striate-nerved; heads panicled or corymbed in our 

 species. 



Pappus-bristles rough or serrate ; involucral bracts numerous. 6. Coleosanthus. 

 Pappus-bristles plumose ; involucral bracts few. 7. Kuhnia. 



Bracts of the involucre faintly striate, if at all ; heads spiked or racemed. 



8. Lactnaria. 



2. Bracts of the involucre in only 2 or 3 series ; all nearly equal. 



9. Trilisa. 



Tribe 3. ASTEREAE. 



A. Ray-flowers yellow (white in one species of Solidago), or wanting: ; plants not 



dioecious. 



* Pappus of scales, or awns, or wanting, never of numerous capillary bristles. 

 Heads small, nor over 4 mrn. high ; leaves narrowly linear, entire. 



Perennial herbs, or shrubs; all the flowers fertile. 10. Gutierrezia. 



Annual herb; disk-flowers sterile. u. Amphiachyris. 



Heads large, showy; leaves oblong to lanceolate, spinulose-dentate. 



12. Grindelia, 



* * Pappus of either the radiate or tubular flowers, or both, of numerous capillary 



bristles, with or without an outer series of shorter ones, or of scales. 

 t Pappus, at least of the disk-flowers, double, an inner series of capillary bristles ', and 



an outer one of scales or short bristles ; heads large. 

 Achenes of the ray-flowers thick, the pappus obsolete, or of a few caducous bristles; 



achenes of the disk-flowers flat. 13. Heterotheca. 



Achenes of both ray-flowers and disk-flowers flattened. 14. Chrysopsis. 



t t Pappus wholly of capillary bristles. 



i. Heads wholly of disk-flowers (in our species): rays none; leaves narrowly linear. 

 a. Perennial herbs: style-tips not exserted: eastern. 15. Chondrophora. 



b. Shrubs; style-tips mostly exserted; western. 

 Involucral bracts gradually narrowed to the tip, keeled, chartaceous. 



16. Chrysothamnus. 

 Involucral bracts cuspidate, flat, herbaceous. 17. Oonopsis. 



2. Heads with both ray-flowers and disk-flowers (in our species). 

 a. None of the leaves cordate; pappus mostly as long as the achene, or longer. 

 Leaves bristly-serrate or pinnatifid. 



Achenes glabrous ; pappus-bristles deciduous. 18. Prionopsis. 



Achenes white-tomentose ; pappus-bristles persistent. 19. Sideranthus. 



