Glossary
Like the rest of this website, the glossary is a work in progress. If we’ve missed a term, please contact us to let us know the term and references.
Porefield
A porefield is an area of fine pores set apart from the pattern on the rest of the valve. Diatoms excrete mucopolysaccarides through the porefield. These extra polymeric substances (EPS) comprise the stalks and pads which attach diatoms to substrates and to sibling cells. There are several types of porefields.
Porefield Types
apical porefield - separated from valve striae by a narrow hyaline area; occurs at valve apex of some araphid (e.g. Diatoma) and some raphid genera (e.g. Cymbella). See illustrations on this page.
ocellulimbus - porefield set into the apex of a valve (e.g. Pseudostaurosira)
ocellus - porefield with a distinct hyaline rim (e.g. Pleurosira)
pseudocellus - porefield lacking demarcation and with pores decreasing in size (e.g. Terpsinoë)
See ocellulimbus, ocellus, and pseudocellus for more detail.
Porefield is a closed compound word combining pore and field. This web flora uses the closed version as it does with the closed compound words headpole and footpole.
Citations
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Publication Link: 10.1111/j.1529-8817.2011.01081.x
Image Credit: Sarah Spaulding
Image Credit: Marina Potapova
Image Credit: Sarah Spaulding
Image Credit: Sarah Spaulding
External view of the apical porefield of Didymosphenia geminata.
Image Credit: Marina Potapova
Internal view of the apical porefield of Cymbella affinis.
Image Credit: Sarah Spaulding
Live cell of Didymosphenia geminata with mucopolysaccaride stalk (at bottom of image) secreted from the apical porefield. The stalk is covered with cells of Achnanthidium minutissimum.