IOWA ACADEMY OF SCIENCE 73 



PLATE I. 



Fig. 1. Longitudinal section of young spike. 



PLATE II. 



Fig. 2. Floral diagram. 



Fig. 3. Mature pistillate flower in longitudinal section. 

 Fig. 4. Mature staminate flower in longitudinal section. 

 Fig. 5. Longitudinal section of spike, showing two adjacent flowers, tlie up- 

 per pistillate, the lower staminate. 



PLATE III. 



Young flowers in axils of developing bracts. 



Sepals beginning to appear. 



Stamens appearing as broad elevations. 



Older stage. 



Petals opposite the outer whorl of stamens. 



Later stage of staminate flower. 



Staminate flower at stage pistils begin development. 



Inner whorl of stamens, opposite calyx. 



Cross section of flower about same stage as Fig. 13. 



Older staminate flower. 



PLATE IV. 



Pistillate flower showing the beginning of the ovules. 

 'Later stage showing sepals and rudimentary calycine stamens. 

 Two developing ovules filling the ovarian cavity. 

 Pistillate flower showing the two lateral bracts. 

 Figs. 20-21. Part drawings of one flower to show difference in size between 



the outer, epipetalous, and the inner, episepalous, staminodia. 

 Fig. 22. Later stage of pistillate flower. 



