Verthylung
As TYLOSE is closing not referred longer used tracheas especially in angiosperms plants.
In the wood of angiosperms there are wide, large-lumen vessels for water transport. In the course of the secondary growth in thickness of the shoot , the growth layer ( cambium ) creates them again and again. The trachea lying further inside are no longer actively involved in the water transport and are no longer required by the plant.
The plant therefore closes these vessels by forming and placing a sack-like protuberance of a neighboring parenchymal cell (thylle) within the trachea. As a connection between the trachea and the parenchyma cell, spot channels between the neighboring cells are usually used. The newly formed thylles can in turn develop their own cell wall and function as an independent cell within the trachea. Your task is then, for example, to store strength .
literature
- Rudolf Schubert, Günter Wagner: Botanical dictionary. 11th edition, Ulmer Verlag, Stuttgart 1993. ISBN 3-8252-1476-1