April, 1921] Reversal of the Sexual State 189 



Ricinus communis L. Castor-oil plant. 



The inflorescence of Ricinus is a panicle with staminate 

 flowers below and carpellate flowers above. Typically the 

 transition from one type of flower to the other is quite abrupt. 

 There are numerous examples, however, in which a flower on 

 the transition zone is bisporangiate. See Fig. 1. In such a case 

 it is evident that the incipient flower bud is in a neutral condi- 

 tion to a rather late stage. Then the incipient tissue at the base 

 of the flower bud goes into the male state and as a result typical 

 branched stamens develop. The tip of the bud passes into the 

 female state and gives rise to the normal three-carpelled gyne- 

 cium. In the staminate flowers immediately below, the male 

 state must be established at the very inception of the flower bud 

 or even earlier and thus the entire bud is in the male state which 

 inhibits completely the development of a gynecium. On the 

 other hand, in the carpellate flowers above the transition zone, 

 the female state is established at the inception of the flower 

 bud and this condition inhibits all development of an andrecium. 



Peltandra virginica (L.) Kunth. Green Arrow-arum. 



This plant has a spadix which is carpellate below and stam- 

 inate above. The carpellate flowers have prominent vestigial 

 stamens while the staminate flowers show no evident vestige 

 of a gynecium. The transition from the carpellate part of the 

 spadix to the staminate is sometimes abrupt, but very fre- 

 quently there is a transition zone of some width, in which case 

 this area is characterized by flowers showing all gradations 

 from normal gynecia to the merest vestige of a gynecium; and 

 finally, of course, the flowers are purely staminate. Figs. 2, 3 

 and 4, represent such a series. Fig. 2 is a normal carpellate 

 flower; Fig. 3, a flower with reduced gynecium, the stamens 

 being still vestigial; Fig. 4, a flower from near the staminate 

 side of the zone with a slender, pointed vestige of a gynecium 

 and the stamens still somewhat imperfect. The next flower 

 above was a normal staminate flower with no vestige of the 

 gynecium. 



Typha latifolia L. Broad-leaf Cat-tail. 



In Typha the carpellate part of the inflorescence is below 

 and the staminate above. The two parts are usually contiguous 

 in the broad-leaf species and usually some distance apart in 



