Pennate vs Centric
Definition
The two morphological groups of diatoms. Pennate diatoms are elongate with bilateral symmetry (Naviculaceae, Pinnularia, Cymbella). Centric diatoms are circular with radial symmetry (Cyclotella, Aulacoseira). Freshwater bodies are dominated by pennate forms.
Related terms
- Acetolysis
- Erdtman's 1934 extraction method. The sample is treated with a 9:1 mixture of acetic anhydride and concentrated sulphuric acid, which dissolves cellulose...
- Aperture
- An opening in the pollen wall through which the pollen tube emerges. Classified by shape into pores (porate), furrows (colpate) and combined...
- Diatom
- A microscopic alga with a silica cell wall (frustule) bearing species-specific surface ornamentation. Diatoms are abundant in freshwater, marine, and brackish environments....
- Diatom Test for Drowning
- Acid digestion of bone marrow (femur or sternum) followed by microscopic examination for diatoms. Diatoms in marrow indicate that water was aspirated...
- Forensic Palynology
- The application of pollen and spore analysis to legal investigations. A forensic palynologist identifies the species composition of pollen assemblages from crime-scene...
- Frustule
- The silica cell wall of a diatom, composed of two overlapping valves (epitheca and hypotheca). Frustules are taxonomically distinctive, chemically resistant to...
- Sexine and Nexine
- The two layers of the pollen exine (outer wall). Sexine is the sculptured outer layer (spines, ridges, reticulum), nexine is the smoother...
Explained in
- Pollens and Diatoms in Forensic InvestigationThe two morphological groups of diatoms. Pennate diatoms are elongate with bilateral symmetry (Naviculaceae, Pinnularia, Cymbella). Centric diatoms are circula...