Pith

The marrow is a soft substance in the core area of plant stem axis. It is the innermost tissue of shoot and root.

In botany, the softer tissue is called in stalk- shaped Thallusgebilden and in the stems and in the roots of higher plants marrow.

Due to the vascular bundles arranged in a ring a scion is in its stem axis ( called stem in herbaceous plants, known in woody plants as the root ) split into two zones:

• The cortical zone and
• Mark the zone.

The Mark is centrally located and is always characterized by pronounced parenchymatous cells form and usually consists of the most cells of the stem. The between the vascular bundles located, Mark and connecting bark strips of the background fabric are called medullary rays.

In the stems of many herbaceous plants and some woody plants ( for example, the elder ) the cell membranes of this tissue are weak thickened, the content is often disappeared from the cells and replaced by air, having died the cell itself. Sometimes are wide, air-containing junctions between the cells present, what is the reason of the characteristic lightness and softness of white paint such a cord.

In some stems of herbaceous plants, the marrow cells die off even in the first period of life before the stalk has finished its growth. You are torn apart and disappear and the stem is then in the adult state hollow ( the medullary cavity of the grasses ). In the woods the marrow is usually permanent, the cell membranes are the same more or less thickened and lignified and in the winter time the starch is deposited in the cells. Nowhere does the marrow to at a later age in scope. In older logs it goes mostly to the innermost parts of the wood, making the hollow Where the tribe begins.

Sources and Literature

• Dtv - Atlas for Biology, 11th edition 2001, ISBN 978-3423032216
• Meyers Encyclopedia of 1889,

• Botany
• Plant tissue
• Wood