stellate parenchyma is a form of aeration tissue (aerenchyma) in plants, which helps with internal air circulation in plants. the tissue is typical of aquatic and wetland plants, and consists of cells with large intercellular spaces that allow air supply to underwater plant parts.
due to the very narrow depth of field at high magnification, the picture is actually a focus stack of 22 combined layers. to get a feeling for the three-dimensional structure of this anatomical section, check out the animation below:
