Valve

A diatom valve is the siliceous unit at one end of a frustule. Two opposite valves and their linking copulae form a frustule.

Diatom taxonomy is largely based on morphology of the valve.

See also frustule, epitheca, hypotheca, copula, girdle band, and cingulum.

S Leptostauron Cruciform
Image Credit: Eduardo Morales
A scanning electron micrograph showing the intricate sculpturing of the outside of a valve of Staurosirella leptostauron. Spines project from the costae, lineolate areolae make up the striae, and porelli (minute openings) compose the apical pore fields.