The Ohio Journal of Science 



Vol. XXII April, 1922 No. 6 



THE SEXUAL NATURE OF VEGETATIVE 

 OR DICHOTOMOUS TWINS OF ARIS^MA.* 



JOHN H. SCHAFFNER 



Department of Botany. Ohio State University 



While studying sex reversal in Arisaema triphyllum (L.) 

 Torr., the writer accidentally came across some interesting 

 examples of dichotomous twins which have a bearing on the 

 theory of sex determination. Twin flower clusters were reported 

 several years ago by Pickettf who discovered about a dozen 

 of such plants. He says the two flower clusters were surrounded 

 by two leaves, and also makes the casual remark that the two 

 clusters "are of the same sex on each plant and are entirely 

 independent, arising from two separate initial groups." 



The twin shoots and separated twins must not be confused 

 with the normal lateral buds, which are produced each season 

 from the corm. The main corm often becomes smaller, not 

 only from accidents to the aerial shoots and poor growing 

 seasons which reduce the available food supply but also from 

 excessive or vigorous lateral bud production. In case of 

 dichotomy of the growing bud which results in twins, one can 

 find all gradations from simple inflorescences with slightly flat- 

 tened spadices ending in two tips and with a double-pointed 

 spathe to individuals which have two entirely distinct aerial 

 shoots, identical in appearance and situated closely side by side. 

 Such pairs of twin shoots become entirely separated after a 

 year or more because of the further development of the two 

 buds and the dying off of the back end of the corm. The twins 

 can often be recognized as such for several years after com- 



* Papers from the Department of Botany,. The Ohio vState University, Xo. 134. 

 t Pickett, F. L. A Contribution to our Knowledge of Arisaema triphvllum. 

 Mem. Torr. Bot. Club. 16:48. 1915. 



149 



