290 COMPOSITE. 



* Pappus paleaceous or aristiform or coroniform, i. e. of chaffy scales or awns Sr of few stout 

 awn-like bristles, or of very short bristles or scales sometimes united in a crown, rarely 

 obsolete or wanting, never of indefinitely numerous capillary bristles. 



-J- Flowers all yellow. 



++ Involucre of coriaceous or firm-chartaceous scales mostly with herbaceous or greenish tips, 



commonly (No. 9 excepted) coated with a resinous or balsamic exudation. 



6. Gutierrezia. Heads small and corymbose or clustered, with rays ; the flowers all fertile. 



Pappus of several short chaffy scales. 



7. Amphiachyris. Heads small, clustered, with fertile rays ; the disk-flowers not fertile. 



Pappus in the disk-flowers of long flatfish and soft bristles rather than scales ; in the 

 few ray-flowers of chaffy scales concreted at base into a cup. 



8. Grindelia. Heads larger, solitary, terminating simple branches, many-flowered, mostly with 



rays and all the flowers fertile. Akenes glabrous. Pappus of 2 to 8 rigid and stout 

 caducous awns. 



9. Acamptopappus. Heads without rays. Scales of the involucre chartaceous, with scarious 



and lacerate-fimbriate margins. Akenes turgid, very densely white-woolly. Pappus 

 persistent, of numerous rigid chaffy awns, the longer ones equalling the corolla. 



++ ++ Involucre of thin more or less imbricated scales, destitute of herbaceous tips. 



10. Pentachaeta. Akenes compressed. Pappus of 5 (rarely 2 to 8) persistent slender rigid 



bristles, sometimes unequal or all very short, sometimes obsolete or wanting. 



-f- -J- Pays white, blue, or purple (never yellow) : disk-flowers yellow : akenes compressed. 



10. Pentachaeta sometimes has white rays in one species. 



1 1 . Monoptilon. Pappus a small crown and a single deciduous bristle which is plumose at top. 



12. Eremiastrum. Pappus of 8 to 10 thin scales cut almost into bristles, and within these 



some stout bristles. Akenes with merely nerved margins. 



* * Pappus of copious slender or capillary bristles. 



+- Flowers all with the limb of the corolla 5-parted into linear or elongated-oblong lobes, either 



regular or the marginal ones palmate : no ligulate rays. 



13. Lessingia. Heads 5 - 25-flowered. Flowers yellow, purple, or white. 



■*-+■ Disk-flowers with the tubular corolla merely 5-toothed or with 5 short lobes, perfect : ray- 

 flowers when present ligulate (pistillate, or in a few cases neutral). 



++ Rays yellow, their akenes destitute of pappus. 



14. Heterotheca. Nearly the same as Chrysopsis (No. 15), except that their larger and 



thicker ray-akenes have no pappus. 



++ ++ Pays yellow or sometimes none : disk-flowers yellow : all the akenes with pappus. 



a. Pappus double. 



15. Chrysopsis. Heads radiate or in one section rayless. Pappus of two sorts ; the interior 



of long capillary bristles, the exterior a set of short bristles or chaffy scales. Akenes 

 compressed. 



b. Pappus simple : involucre imbricated. 



16. Aplopappus. Heads radiate, excepting one or two species which have more or less folia- 



ceous or green-tipped scales to the involucre, commonly broad and solitary, or somewhat 

 clustered, usually large or middle-sized. Bristles of the pappus copious and unequal, 

 somewhat rigid. 



17. Bigelovia. Heads rayless (rarely an imperfect ray or two), homogamous, mostly cymosely 



or corymbosely clustered, and narrow. Scales of the involucre dry, coriaceous or com- 

 monly chartaceous, appressed, rarely with green tips. Bristles of the pappus copious 

 and unequal. • 



18. Solidago. Heads radiate, narrow, numerous and mostly small, racemed or panicled, or 



sometimes cymose. Scales of the narrow involucre appressed, destitute of herbaceous 

 tips. Bristles of the pappus equal and nearly in a single series, slender. Style-append- 

 ages lanceolate or broader, never filiform. 

 ++ ++ ++ Rays white, purple, or blue, never yellow ; disk-flowers yellow, rarely turning purplish. 



19. Sericocarpus. Pays few (about 5, white) : disk-flowers rather few. Involucre narrow, im- 



bricated, of appressed firm-coriaceous white scales with abrupt green tips. Akenes 

 silky, not flattened. Pappus copious, simple. 



20. Corethrogyne. Rays mostly sterile ! (the style wanting and the ovary abortive), numerous 



in a single series. Involucre imbricated. Style-appendages of the disk-flowers thickly 

 beset with long bristles, forming a brush-like tuft. Akenes flattened. Pappus simple, 

 of pretty rigid unequal bristles. 



