Fig. 7. Normal Aster florets, r ray, d disc. 



flower the less seed it produces. A perfectly double flower produces 

 no seed unless pollen is brought to it by insects from other more 

 single flowers. 



Fig. 10. Normal and affected pistils 

 showing enlargement by Vellow Disease. 

 n normal, d diseased. 



Fig. 12. Longitudinal sections of young 

 florets showing normal {b) and affected (rt) 

 ovules and pistils. 



