Volume 14 Numb«- 11 



The Plant World 



A Magazine of General Botany 

 NOVEMBKR, 1911 



CERTAIN PHASES OE THE BEHAVIOR OE THE STIGMA 

 LIPS IN DIPLACUS GLUTINOSUS NUTT. 

 Francis E. Lloyd 



The Bush IMonkey-Elower, DipJaciis, the monotype of its 

 genus, possesses, in common with MimuliiSf Torenia and Mar- 

 tynia a sensitive two-lipped stigma. Responding to the tempta- 

 tion of an abundance of material growing at Carmel, California, 

 near the Botanical Laboratory of the Carnegie Institution of 

 Washington, during the summer of 19n, I attended somewhat 

 closely to certain features of the behavior of the stigma lobes, 

 with the result that there emerged conclusions at some variance 

 with those stated in current text-books, and indeed with those 

 of previous investigators. 



Correns * in his study of the dependence of irritable phe- 

 nomena upon the presence of free oxygen included in an exten- 

 sive series of forms examined by him, the movements shown by 

 the r.tigma lips of Mimuliis moschatus and M. luicus. He ob- 

 served that the li- s close under reduced atmospheric pressure, 

 but showed that this is due to the reduction of the oxygen ten- 

 sion, and not to any physical effect of the reduced pressure. If 

 the period of exposure is too long, the lips remain closed, but if 

 not, they open again and respond to mechanical stimuli as be- 

 fore. A similar behavior was observed on exposure to ammonia 

 gas. Correns regards the change in the amount of oxygen as the 

 stinuilus, since • s effect is analagous to that due to variation in 

 the amount of light, as in the case of Mimosa. Ammonia, how- 

 ever, he believes to be a chemical stimulant. 



♦Correns, C. Ueber die Abhiingigkeit der Reizerscheinungen hoherer Pflanzen von der 

 Gegenwart freien Sauerstoffes. Flora 75:87-151 1892. 



