DEVELOPMENT OF PLANTS 



439 



etc. The majority of such forms have horned anthers which 

 are shaken by the insect and so assist in sifting out the spores. 

 In the blueberry family, we note that an adhesion of the recep- 

 tacle and ovary has begun (Fig. 327, D) while in Rhodora, 

 rhododendron and azaleas another line of variation appears in 

 the irregular corolla (Fig. 327, F). In the two latter genera, 

 the styles and stamens extend far out, furnishing a natural land- 

 ing place for hovering animals as moths and humming birds. 



FIG. 327. Common forms of Ericales : A, Indian pipe (Monotropa}. 

 Leaves reduced to scales and without chlorophyll, owing to saprophytic 

 habit of plant. B, section of flowers, showing polypetalous corolla. C, 

 inflorescence of the blue berry (V 'actinium) . D, section of flower, show- 

 ing sympetalous corolla and epigynous type of flower. E, a stamen en- 

 larged, opening by pores at end of anther. F, azalea, showing irregular 

 type of flower. G, spores attached by viscid threads. 



In this position the spores cannot be sifted out and we find them 

 fastened together in fours, just as they were formed in the 

 mother cell, by sticky threads which cause them to adhere to 



