86 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



Pappus a cluster of short, stout bristles 

 Pappus of long, capillary bristles: 

 bristles few 

 achene nerveless 

 5-nerved 



bristles numerous 

 achene constricted into a neck 

 (section) biconvex 

 (section) concavo-convex 

 (section) quadrilateral 

 achene devoid of a neck 

 compressed: 

 ribs 10, smooth 

 ribs 8, rugose 

 subterete: 

 apex discoid 

 apex not discoid 



Pappus of slender, barbed bristles: 

 achenes (section) pentagonal 

 terete 



quadrilateral 

 2-nerved, pubescent 

 8-nerved, glabrous 

 achene (section) oblong 



lenticular 



Pappus of plumed bristles: 

 achene cylindrical, obconoid 

 achene lenticular, oblanceolate 

 Pappus of equal scales: 

 achene pentagonal, oblong 

 achene 12-angled, turbinate 

 achene lenticular, obconoid 

 Pappus of unequal scales 

 Pappus of awns: 

 awns united at the base 

 awns distinct 

 achene obovate 

 winged, attenuate at base 

 wingless, not attenuate lenticular: 

 awns very slender 

 awns unequally winged 

 wingless, not attenuate, flattened 

 achene linear: 

 awns smooth 

 awns barbed 



achene fusiform attenuate into a neck 

 Pappus of awns and scales: 

 achenes constricted into a neck 

 neck curved, awns prominent 

 neck erect, awns inconspicuous 

 achenes not constricted 

 quadrilateral 

 sharply 3-4-angled 

 lenticular 



lo-ribbed, awns genuflexed 

 not ribbed, awns straight: 

 scales connate 

 achene obovate 

 achene linear 



Pappus of scales and bristles: 

 bristles equal, distinct 

 bristles unequal, united below 



Spiracantha. 



Conyza. 

 Pluchea, 



Porophyllum. 



Chaptalia. 



Lactuca. 



Baccharis. 

 Sonchus. 



Erechtites. 

 Senecio. 



Eupatorium < 

 Coleosanthus 



Willughbcea. 



Leptilon. 



Aster. 



Pectis % Pectothrix. 



Trixis. 



Tridax. 

 Carduus. 



Agerattim. 



Helenium. 



Calea. 



Pectis % Eupectis, 



Ucacou. 



Verbesina. 



Spilanthes. 



Salmea. 



Encelia. 



Pectis % Pectidium. 



Bidens. 



Cosmos. 



Plagiolophus. 

 Zexmenia 



Tithonia. 



Zexmenia % Lipoch&ta. 



Distreptus. 



Viguiera. 

 Tagetes. 



Vernonia. 

 Dysodia. 



