406" SYNGENESIA SUPERFLUA. 



326. LACTUCA. Calyx imbricate, cylindrical; scales membranace- 

 ous at the margin ; receptacle naked ; pappus simple, stipitate. 



327. 8ONCHXJS. Calyx imbricate, swelling at the base; receptacle 

 naked ; pappus simple, sessile. 



328. H1ERAC1UM. Calyx imbricate, ovate; receptacle nearly punc- 

 tate ; pappus simple, sessile. 



329. KRIGIA. Calyx many-leaved, simple; receptacle naked; pap- 

 pus double ; exterior 5 8-leaved ; interior of 5, 8, or 24 scabrous 

 bristles. 



* * Fiords all tubular, forming a hemispherical head. 



330. ARCTIUM. Calyx globose, with the scales hooked at their ex- 

 tremity ; receptacle chaffy ; pappus setaceous-chaffy. 



331. ONOPOP.^ON. Calyx ventricose, imbricate, with spreading spi- 

 nous scales ', receptacle pitted ; pappus capillary, deciduous, scab- 

 rous. 



332. CNICUS. Calyx ventricose, imbricate, with spinous scales; 

 receptacle hairy ; pappus deciduous, plumose. 



333. LIATRIS. Calyx oblong, imbricate; receptacle naked; pap- 

 pus plumose, persistent, (mostly colored;) seed pubescent, striate, 

 obconic. 



334. VERNONIA. Calyx ovate, imbricate; stigma bifid; pappus 

 double ; exterior short and chaffy ; interior capillary. 



* * * Florets all tubular, erect, forming a nearly level top. 



335. EUPATORIUM. Calyx imbricate, oblong ; style much exsert., 

 deeply cleft ; receptacle naked ; pappus scabrous ; seeds 5-striate 

 or angular. 



336. MIKANI A. Calyx 4 6-leaved, 4 6-flowered ; receptacle naked ; 

 pappus hairy. 



SUPERFLUA. 



* Florets of the ray obsolete. 



337. TANACETUM. Calyx imbricate, hemispherical ; scales acumi- 

 nate ; rays of the corolla obsolete, trifid ; receptacle naked ; papput 

 somewhat margined. 



338. ARTEMISIA. Calyx ovate, imbricate; scales rounded, conni- 

 vent ; florets of the ray subulate ; receptacle subvillous or naked ; 

 pappus 0. 



330, CONYZA. Calyx imbricate; scales often subscarious ; recepta- 

 cle naked. Marginal florets fertile, 3-cleft ; pappus simple and ca- 

 pillary. 



340. GNAPHALIUM. Calyx imbricate ; scales scarious, mostly col- 

 ored ; receptacle naked ; Jlorets of the ray subulate ; fertile floreti 

 entire ; pappus scabrous. 



* * Florets of the ray ligulate. 



341. EPJGERON. Calyx imbricate, subhemispherical ; Jlorets of tha 

 ray very numerous and narrow ; receptacle naked ; pappus double 

 exterior minute; interior hairy, of few rays. 



