Figure 5. Different morphs of Fragilaria construens from Avery Pond, CT (USA) as shown by SEM. First column: typical morphs of F. contruens, F. construens aff. var. subsalina and F. construens var. venter. Second column: morphs with wider areolae arranged in shortened striae. Third column: morphs with wider areolae arranged in longer striae. Scale bars (from top to bottom): first column: 2, 5, and 2 µm; second column: 2, 2, and 2 µm; third column: 2, 2, and 2 µm.