Glossary

Pennate diatoms are bipolar, elongate and bilaterally symmetric, although quite a few taxa are bilaterally asymmetric. Pennate diatoms make up a heterogeneous group that includes araphid, monoraphid, and biraphid taxa.

In older taxonomic systems, pennate diatoms are contrasted with the centric diatoms. These two groups are not natural, evolutionary lineages but serve as general descriptions of morphology.

In Latin, pennate means feathered, chosen perhaps because a valve resembles the vane of a feather and striae resemble the barbs of a vane.