Porte-crayon

A porte-crayon is a pointed, hyaline area that surrounds the distal end of the raphe. It is formed by the joining of the longitudinal ribs that lie along each side of the raphe. Porte-crayons are found in the genera Frustulia and Amphipleura. In French, porte-crayon means pencil holder.

Citations

Round, F.E., Crawford, R.M. and Mann, D.G. (1990) The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

frustulia-rexii-porte-crayon — Apex of *Frustulia rexii* (LM). Longitudinal ribs fuse to form a prominent porte-crayon. Scale bar = 10 µm.