Having the shape of a club. Usually applied to describe the asymmetry of Gomphoneis and Gomphonema in
Barber, H.G. and Haworth, E.Y. (1981). Guide to the Morphology of the Diatom Frustule.
Freshwater Biological Association, 112 pp.
Image Credit: Pat Kociolek
The valve margins of Gomphoneis olivaceum are clavate in shape.