April, 1921] Reversal of the Sexual State 197 



EXPLANATION OF PLATES I AND IL 



All the drawings were originally magnified and then reduced in the repro- 

 duction of the plates. 



Ricinus communis L. 

 Fig. 1. Bisporangiate flower from the transition zone between the staminate and 

 carpellate parts of the inflorescence. 



Peltandra virginica (L.) Kunth. 

 Fig. 2. A normal carpellate flower showing the character of the gynecium and 



the prominent vestigial stamens. 

 Fig. 3. A flower from the transition zone showing the gynecium greatly reduced. 

 Fig. 4. A flower from the transition zone, near the staminate part of the inflores- 

 cence, showing a small vestigial gynecium with an elongated tip 

 and 4 vestigial stamens. The normal staminate flowers have no 

 vestige of carpels. 



Typha latifolia L. 



Fig. 5. Normal carpellate flower, showing the leaf-like stigma. 



Fig. 6. A normal stamen. Staminate flowers may have two or more stamens 

 on a common pedicel. 



Fig. 7. A flower from the edge of a staminate area invading the carpellate part 

 of the inflorescence, showing a stigma-like structure with two 

 imperfect pollen sacs containing microspore tetrads. 



Fig. 8. A stamen-carpel complex from the edge of a staminate patch in the 

 carpellate part, showing one anther and a twin structure which has a 

 pollen sac on one side and a stigma-like structure on the other. 



Arisaema triphyllum (L.) Torr. 



Carpellate flower or gynecium from the edge of a staminate area in a 

 carpellate inflorescence showing an anther growing out of one side. 



Gynecium from the edge of the transition zone between the lower carpel- 

 late area and the upper staminate, showing two anthers growing from 

 its side. 



Gynecium from the top of a carpellate inflorescence with an anther on 

 its side. Otherwise the inflorescence was completely carpellate. 



Gynecium somewhat rudimentary with a stamen growing from the side 

 lying next to or partly within the staminate spot of the inflorescence. 



Flower from transition zone between the staminate and carpellate parts 

 of an inflorescence, showing a stigma on one side and four anthers and 

 irregular stigmatic and distorted masses on the other. 



Flower from the transition zone consisting of a small rudimentary 

 gynecium with three pollen-sacs growing out of the side next to the 

 staminate patch of the inflorescence. 



A flower on the line dividing the staminate and carpellate parts of an 

 inflorescence showing a carpellate structure with stigma on one side 

 and a staminate structure with two pollen-sacs on the other. 



A number of flowers on the transition zone; one with a rudimentary 

 stigma and ovulary from which two large anthers have developed. 



An area on the transition zone showing two normal carpellate. flowers 

 on one side and two staminate flowers on the other with three rudi- 

 mentary gynecia; one a normal gynecium but considerably reduced, 

 the middle one vestigial, and the third one developed as a long, horn- 

 like neutral structure. 



Myriophyllum heterophyllum Mx. 



Fig. 18. A carpellate flower from the lower part of the inflorescence, showing the 

 large stigmas, minute vestigial stamens, and very small petals. 



Fig. 19. A flower from near the base of the transition zone of the inflorescence, 

 showing petals and vestigial stamens much larger than in the carpellate 

 flowers below and having the stigmas somewhat reduced. 



Fig. 20. A flower from near the base of the transition zone with apparently normal 

 stigmas, with intermediate petals and enlarged vestigial stamens, one 

 stamen being considerably longer than the other three. 



