192 The Ohio Journal of Science [Vol. XXI, No. 6, 



and the staminate flowers have vestigial ovules. There is every 

 gradation of size and completeness between the two extremes 

 across the transition zone. Figs. 18-24 represent such a suc- 

 cession. Fig. 18 is a typical carpellate flower. In Fig. 19 the 

 petals and stamens are considerably larger while the stigmas 

 are reduced. Fig. 20 represents a stage somewhat nearer the 

 carpellate flower altho the petals are larger. One of the 

 stamens is considerably more developed than the others while 

 the stigmas are nearly normal. In Fig. 21 the structures are 

 nearly all intermediate between the two extremes. In Fig. 22 

 the stamens are prominent tho still imperfect, the petals 

 approach the staminate type, while the stigmas are much 

 reduced. Fig. 23 represents a normal staminate flower above 

 the transition zone, just before the petals unfold and the 

 fllaments elongate. The petals have been removed. One of 

 them is represented in Fig. 24. 



Zizania aquatica L. Wild Rice. 



The panicle of the wild rice is staminate below and carpellate 

 above. If one examines a branch on or near the transition 

 zone of the main axis, he finds first staminate spikelets, then 

 bisporangiate spikelets, often with perfect andrecia and gynecia 

 and finally at the tip normal carpellate spikelets. The lemmas 

 of the staminate spikelets are awnless while those of the car- 

 pellate ones are long-awned. On the transition zone, one can 

 find spikelets with awns of every conceivable intermediate 

 length. The awn of the wild rice is a prominent sex-limited 

 character and its length depends on the intensity of the stam- 

 inate or carpellate state present, or on the earliness or lateness 

 of the time that the sexual state is developed in the spikelet or 

 its glumes. Fig. 25 represents a staminate flower with all the 

 stamens removed except one. The gynecium is quite vestigial 

 because of the presence of the male condition. Fig. 26 repre- 

 sents the same gynecium highly magnified. The third vestigial 

 stigma is considerably smaller than the other two. This stigma 

 is vestigial in a phylogenetic sense while the other two are onto- 

 genetically vestigial on account of the inhibitory action of the 

 male state in the flower. Fig. 27 represents a bisporangiate 

 flower from the transition zone. Only one stamen is repre- 

 sented. The gnyecium, not quite mature, is normal with typical 

 ovulary and stigmas. Fig. 28 represents the gynecium and 



