Gas Exchange in Plants

Air Spaces in Plant Tissues

Leaf tissue has a well-developed aeration system consisting of interconnected intercellular spaces. These air spaces develop either by a pattern of cell division that leaves spaces empty or by the rupture of certain cells. Air spaces are particularly important in aquatic plants, where air spaces usually are large and constitute a greater proportion of the plant's volume. In addition, the air systems of aquatic plants appear to be continuous from leaf to root, giving aeration and buoyancy to the plant. The SEM below shows parenchyma in the petiole of a water lily leaf, which is a floating leaf. Notice the abundant, large intercellular spaces. SL = sclereids, which improve the tissue's mechanical support.

SEM of parenchyma tissue in floating leaf of the water lily.