

550 



Subject Index 



Xeromorphy, and drought resistance, 

 326 

 influence of immature leaves in, 327 

 and nitrogen deficiency, 329 

 Xerophytes, 324 



Xylem and phloem, developmental rela- 

 tions, 84 



Zalenski's law, 325 



Zamia, 237, 250 



Zea, 77 



Zinc, role in development, 37] 



Zinnia, 34, 261 



Zonation in meristems, 64 



Zygomorphic flowers, 176 



