Cell of Actinotaenium turgidum. Notice large cell dimensions and parietal chloroplast bands (in optical cross section). In the central vacuole a large number of crystals are accumulated.
Cell dimensions (L x B): 200 x 80 µm
A. turgidum is readily to be recognized by its large cell dimensions. With a cell length up to more than 200 µm and a cell width up to about 100 µm it holds as the largest European Actinotaenium species. Linked to these large dimensions (so a relatively low cell surface to cell volume ratio) A. turgidum is characterized by parietal chloroplast bands instead of an axial chloroplast as in smaller-sized Actinotaenium species. In the Netherlands, A. turgidum is rather common in mesotrophic quivering fen hollows in the Holocene area but elsewhere it is rare.
Another cell of A. turgidum well showing the parietal chloroplast bands (each with several pyrenoids).
Image © Henk Schulp
Dead, empty cell of A. turgidum showing cell wall with coarse pore fields.