XVI International Botanical Congess

Modifications linked with leaf-lobe movement were studied in three-layered region including motor zone. Rapid movement is accompanied by folding of thin anticlinal walls in all three cell layers. Volume of upper (UE) and lower (LE) epidermal cells decrease twice, of middle layer (ML) cells nearly in 7 times. Bundle sheath cells change shape dramatically too. In UE and LE large vacuoles form many small ones. Vacuoles with fibrillar content without tannins appear. Spherical tannin aggregations surrounded by filaments appear in vacuoles. Vacuoles in LE have smaller tannin spheres and more filaments then ones in UE. In contrast vacuole in ML cells stays central with transparent vacuole content. Membranes in periplasmic area form relatively large vesicles. Therefore all three cell layers take part in trap lobe movement. Structural modifications linked with movement are similar to that ones in seismonastic plants pulvini.