ABSTRACT
Pistia stratiotes L. is a free-floating plant which belongs to the family Araceae, order Spadiciflorae. Dense vegetation of Pistia may seriously threaten human health, as its root system provides a favorable habitat for the larvae of certain disease-carrying mosquitos, like the Mansonia mosquito, the vector of encephalomyelitis and filariasis. Pistia occurs throughout the tropics and the subtropics. Experiments on the effect of temperature on flowering of Pistia have not been conducted. However, in The Netherlands where during various summers Pistia has been released in the field, flowering has only been observed at a few sites during the extremely hot summer of 1976. Outside the Lemnaceae and Pistia, salicylic acid has only been observed to affect flowering in the unrelated Balsamina impatiens cv Rose. EDDHA and salicyclic acid also induce flowering in several species of the Lemnaceae, a family which is distantly related to P. stratiotes. As a consequence it could be hypothesized that there are similarities in the flowering mechanisms.
