Fig. 771: Bidens frondosa: a, inner phyllary, x 6; b, receptacle bract, x 6; c, disk 

 flower, X 6; d, mature achene, showing divergent pappus awns with retrorse barbs, and 

 margins of achene with ascending hairs, x 4; e, flowering head, showing the foliaceous 

 outer phyllaries, x %; f, habit, upper part of plant, x %. (From Mason, Fig. 352). 



