MONOPETALOUS EXOGENOUS PLANTS. 353 



3-ribbed; ray:^ 1-5, yellow; aclioiia wingless; corym'bs 

 tricliotomous. 



GAILLARDIA, Foiig. 



Heads many-flowered, the rays nentral, decidnons ; scales 

 of the involucre in 3 rows, acute, spreading above ; recep- 

 tacle convex or hemispherical, naked or fimbrillate ; rays 

 wedge-shaped, palmately 3-lobed ; corolla of the disk with 

 subulate lobes ; aclienia top-shaped, hairy ; papims of G-10 

 membranaceous l-nerved awned scales. — Pubescent branch- 

 ing lierhs, with alternate leaves, and solitary heads of yellow 

 or purple flowers terminating the branches. 



G. LANCEOLATA, Michx. Stem (l°-2°) with long and 

 slender branches; leaves narrow-lanceolate, mostly entire, 

 sessile, the lowest narrowed at the base ; rays yellow, some- 

 times wanting; disk-flowers purple; receptacle naked; 

 scales of the pappus 7-9. 



PALAFOXIA, Lagasca. 



Heads many-flowered, the rayfloiuers pistillate or none; 

 scales of the obconical involucre in 2 rows, membranaceous 

 at the summit; receptacle flat, naked; aclienia slender, 

 4-angled, tapering at the base ; pappus of 6-12 membrana- 

 ceous denticulate scales, pointed by the prolonged rigid 

 midrib. — Herbs or shrubs, with narrow entire leaves, and 

 heads of white or purple flowers in a terminal corymb. 



P. INTEGRIFOLIA, Torr. and Gray. Stem (2° high) 

 branched above, smoothish ; leaves lanceolate, rough, the 

 lower ones often opposite; rays none; floiuers purplish; 

 scales of the pappus 8-9, linear subulate. 



HYMENOPAPPUS, L'Her. 



Heads many-floAvered, the flowers all tubular and perfect; 



