Anatomic insights into the thigmonastic style tissue in Marantaceae.

The irreversible style movement in Marantaceae is one of the quickest plant movements ever recorded. It is largely based on a special tissue construction, which is analysed herein for the first time. Histological sections, fluorescence and different electron microscopic techniques are used to study the style tissue of eight species in six genera of the Marantaceae. Tissue sections prior to the thigmonastic movement are only obtained after ether or chloroform narcosis. The tissue in the bending zone of the style has the construction of a lamellar collenchyma with elongated cells and extended intercellular spaces. The thicker cell walls abut the intercellular spaces, while the thinner walls between adjacent cells are extraordinarily porous. The tissue is thus characterised by strongly perforated cell bundles which are able to slide alongside each other and the intercellular spaces. Cell-wall loosening starts about 24 h before flowering and is interpreted as a result of enzymatic ageing processes. It is also found in other members of the Zingiberales, but only the Marantaceae take advantage of the maceration process. We conclude that the specific tissue construction contributes to the rapid style movement. It combines qualities for stabilisation (collenchyma), pliability (intercellular spaces) and water transport (extremely porous tissue), thus supporting the irreversible style bending by a sudden and final shift of fluid. [ABSTRACT FROM AUTHOR]