Fig. 770: a-d, Bidens discoidea: a, top of plant, x i,^; b, head, x 2^^; c, bract, 

 X ly-y, d, achene, x 5. e-k, Bidens pilosa: e, top of plant, x V-y, f, head, x IV-S, g, disk 

 flower, x 5; h, interior involucre Ijract from side, x 5; i, interior involucre bract, x 

 5; j, inner achene, x 5; k, outer achene, x 5. (V. F.). 



