Glossary terms starting with "f"

Fascia

A hyaline area of thickened silica extending from the central area of some pennate diatoms. A transverse fascia is formed by secondary deposition of silica into depressions on the valve. Examples of genera having a transverse fascia include Luticola and Staurophora. Plural form is facsiae.

See also stauros for a similar structure.

Fascicle

Series, or bundle, of rows of areolae oriented radially in some centric diatoms.

Fibula - keel puncta

Internal strut that provides structural support to the canal that contains the raphe. Plural form is fibulae. The fibulae extend transapically from the raphe canal to the valve face. Examples of genera having fibulae include Denticula, Nitzschia, and Surirella. From Latin for clasp, pin, or brooch.

 

Filiform

Having the shape of a thread.

Foot pole

The narrower pole, or apex, of the valve in genera having the shape of a club. Often has a pore field. Examples include Didymosphenia, Gomphoneis, and Gomphonema.

 

Foramen

The large opening in one wall of a loculate areola. Located on the external or internal wall of the areola, depending on species, opposite the velum. Plural form is foramina.

Frustule

The siliceous parts of the diatom cell wall. Composed of the larger epitheca and the smaller hypotheca. The epitheca overlaps the hypotheca similar to a pill box or Petri dish. From Latin for a little piece.

See also valve and cingulum.

Fultoportula - strutted process

A tubular process of some centric diatoms. The fultoportula consists of a central tubular process surrounded by two or more satellite pores. Externally, the fultoportula appears as either a tube or a simple pore in the valve wall. The plural form is fultoportulae.

Usually associated with the secretion of ยง-chitin to maintain buoyancy in the plankton.

 

Fusiform

Having the shape of a spindle. Broadest at the middle and tapering at both apices.