Stalked rhizomes of the bulrush (Schoenoplectus lacustris (L.) Palla) contain an oxygen gradient from the shoot to the rhizome. The internal oxygen concentration does not fall below 10 %, even if the environment of the rhizome is oxygen free. The oxygen provision is used up 1 h after cutting the stalk. Plants in their natural habitat behave in the same way.

The difference in oxygen uptake between stalked rhizomes and rhizomes without stalks demonstrates an apparent oxygen transport. The calculation of the true oxygen transport shows, that more than 70 % of the oxygen used is delivered from the shoot. Shortening of the stalk improves the oxygen supply of the rhizomes

The good oxygen supply is also demonstrated by the high values of the energy charge (>0.8). Unstalked rhizomes have intermediary valus (0.5—0.7).

From these results we conclude that efficient oxygen transport is the main strategy in relation to the flooding tolerance of this plant