290 



COM POSIT J-: 



♦ Pappus paleaceous or aiistifonn or coroniforni, i. e. of chatFy scales or awns or of few stout 

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

 obsolete or wantiiiy, never of indetinitely numerous capillary bristles. 



+- Flowoiu all yellow. 



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



commonly (No. i) o.Kceiilud) coated with a rosinouu or balsamic o.xudation. 



6. Gutierrezla. Heads small and coiymbose or clustered, with rays ; the ilowers nil fertile. 



I'uppus of several short chaify scales. 



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



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

 few ray-llowers of chafl'y scales concreted at base into a cup. 



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



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

 caducous awns. 



9. Acaxnptopappus. Heads without rays. Scales of the involucre chartaceous, with scarioua 



and lacerale-Hmbriate margins. Akenes turgid, very densely white-woolly. Pappus 

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



++ ++ Involucre of thin more or less imbiicated 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. 



+- +- Hays white, blue, or purple (jiever yellow) : disk-flowers yellow : akenes compressed. 



10. Pentachaeta sometimes has white rays in one species. 



11. Monoptilon. Papjuis a small crown and a single deciduous bristle which is plumose at top. 



12. Eremiastrum. riiin)us 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. 



■i-+- Disk-flowers with the tubular corolla* merely 5-toothed or with 6 short lobes, perfect : ray- 

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



+t 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. 

 ++ ++ Rays 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 chaliy scales. Akenes 

 compressed. 



b. Pappus simple : involucre imbricated. 



16. Aplopappus. Heads radiate, exceiiting 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, naiTow, numerous and mostly small, racemed or panicled, or 



.sometimes cymose. Scales of the narrow involucre njipressed, destitute ot herbaceous 

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

 ages lanceolate or broader, never iililorm. 

 ++ ++ ++ Hays white, purple, or blue, never yellow : disk-flowers yellow, rarely turning jjurplish. 



19. Sericocarpus. Rays few (about 5, white) : disk-ilowers 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-ai)pendages of tlie disk -flowers thickly 

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

 of pretty rigid unequal bristles. 



