Leaf-movements of plant mostly fall into two categories: rhythmic slow leaf-movement in nyctinastic plants, and more rapid seismonastic movements, that occur in a limited number of the nyctinastic plants. The rapid leaf-movement of Mimosa pudica L. is most well-known of all the plant movements. It has been already verified in the early beginnig of 20th century that this movement is caused by some chemical substances. But, identification them has been unsuccessful, and thought to be impossible. However, we have succeeded in the isolation of chemical factor for the leaf-movement of mimosa plant. That is the mixture of three chemical substances, two of the three were identified as potassium malate and magnesium transaconitate. The mixture of these chemical substances was effective at 10^<-8>-10^<-9>M. And all these three components were necessary for causing leaf-movement. Nyctinastic movement in the circadian rhythm observed in plants is known to be controlled by an internal clock. We have isolated several bioactive substances that cause the leaf-closing movement in these plants, e.g. potassium chelidonate (2) from Cassia mimosoides L., trigonelline (3) from Aeshenomene indica L., and phyllanthurinolactone (4) from Phyllanthus urinaria. Each leaf-movement factor was effective at the concentration of 10^<-6>-10^<-7>M, and only for the original plant, not for other nyctnastic plants. This result strongly suggests the existence of different leaf-movement factor in every nyctinastic plants. Recently, we have isolated two inversely effective leaf-movement factors, potassium D-idarate (5) as leaf-closing factor and potassium lespedezate (7) as leaf-opening factor from one nyctinastic plant, Lespedeza cuneata G. Don., and the MeOH-extract of the plant had inverse bioactivity between daytime and night. Thus, the nyctinastic leaf-movement is controlled by the balance in the concentration between inversely effective bioactive substances.
