66 



2 Pappus in marginal florets absent, in disk florets 



scaly, 

 2 Pappus none. Heads compound. 

 3 Pappus in marginal florets none, in disk florets of 



5-6 bristles, which are barbellate at apex. 

 3 Pappu-s in one row. Marginal florets in one row. 

 3 Pappus in one row. Marginal florets 3-6, disk 



florets about 15, all fertile. 

 3 Pappus scabrous. Marginal florets 3-6, disk florets 



1-2, all fertile. 

 3 Pappus in two rows. Involucre squarrose. 

 3 Pappus copious, in one row. Involucre hemis- 

 pherical. 

 3 Pappus copious, in one row. Marginal florets in 



many rows. 

 3 Pappus scanty, plumose. Marginal florets hidden 

 in axils of outermost involucral scales. 

 4 Receptacle with or without palae. 

 4 Receptacle without palae. 

 4 Receptacle with palae. 

 5 Receptacle nude. Heads 1-flowered. 

 5 Receptacle nude Heads many flowered. 

 5 Receptacle fimbrilliferous. Leaves fascicled, 



nispid. 

 f) Receptacle paleaceous. leaves solitary, glabrous. 

 6 Style arms truncate. 

 6 Style arms rotundate. 

 7 Pappus of '2-0 keeled scales 



7 Pappus of 10-16 s(^ales, all or half of them awned. 

 8 Perfect florets sterile 

 8 All florets fertile 

 9 Heads heterogamous Pappus in two rows. 

 9 Heads heterogamous. Pappus in many rows. 



Denekia. 

 Sph^ranthus. 



x\MPHUX)XA. 



Helichrysum. 



Cassinia. 



achyrooline. 

 Leontonyx. 



BOJERIA. 



Gnaphalium. 

 Petalactella. 



Stoebe. 

 Metalasta. 



Nestlera. 

 Rrlhania. 



Callilepis. 



Geigeria. 



Macowaxia. 



Aterixia. 



pulicakia. 



Pkixtzia. 



HELIANTHOIDE^. 

 Heads many-flowered, small Perfect florets with 



undivided styles. Receptacle paleaceous. Parthenium. 



Heads unisexual, monoecious Xantiiium. 



Heads heterogamous, radiate. Receptacle conical 



or cylindrical. Zinnia. 



Heads heterogamous, radiate Receptacle flat or 

 convex. 

 1 Inner involucral scales embracing the achenes. SiKnESBECKiA, 

 1 Inner involucral scales free. Receptacle flat, 



narrow. Eclipta. 



1 Inner involucral scales free. Pappus of 2-4 



rigid bristles Bidens. 



1 Inner involucral scales free. Pappus feathery. Tridax. 

 1 Pal® of receptacle embracing the achenes. 



