Setting-up tension in the style of Marantaceae.

The Marantaceae stand out from other plant families through their unique style movement which is combined with a highly derived form of secondary pollen presentation. Although known for a long time, the mechanism underlying the movement is not yet understood. In this paper, we report an investigation into the biomechanical principles of this movement. For the first time we experimentally confirm that, in Maranta noctiflora, longitudinal growth of the maturing style within the 'straitjacket' of the hooded staminode involves both arresting of the style before tripping and building up of potential for the movement. The longer the style grows in relation to the enclosing hooded staminode, the more does its capacity for curling increase. We distinguish between the basic tension that a growing style builds up normally, even when the hooded staminode is removed beforehand, and the induced tension which comes about only under the pressure of a too short hooded staminode and which enables the movement. The results of our investigations are discussed in relation to previous interpretations, ranging from biomechanical to electrophysiological mechanisms.