Oocardium
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Oocardium is a genus of algae from the order of the yoke algae (Zygnematales).
description
The cells remain small, 7 to 20 micrometers in length. They form colonies of 1 to 2 millimeters in size that are attached to solid substrates. The cells are located at the end of branched gelatinous stems in self-made tubes made of lime. The cell axis is always at right angles to the axis of the tube, which is often misrepresented on drawings. The cells are usually laterally asymmetrical and slightly compressed. In the middle there is a slight constriction where the smooth cell walls of the two cell halves overlap. Oocardium species usually have an axial chloroplast with a central pyrenoid per cell halfon. Sometimes the chloroplasts can also be pressed to one side of the half-cells. The cell nucleus is located between the chloroplasts in the area of the constriction.
Occurrence
Oocardium species are found in the calcareous regions of Europe, North America and India. They are considered rare. Their colonies sit on stones, twigs, leaves, mosses and feathers in calcium- rich rivers with pH values between 7.5 and 9.3.
Systematics
The genus Oocardium was first described by Carl Wilhelm von Nägeli in 1849 . The type species is Oocardium stratum .
- Oocardium depressum Wallner P
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Oocardium stratum Nägeli
- Oocardium stratum var. Intermedium Woronichin P.
- Oocardium stratum var. Minus N. Carter P
- Oocardium stratum f. minus Voronikhin P
supporting documents
- Oocardium at algaebase.org (accessed November 6, 2010)
further reading
- Nägeli, C. (1849): Genera of unicellular algae, physiologically and systematically processed . New memoranda of the General Swiss Society for the Whole Natural Sciences 10 (7): i-viii, 1-139, pls I-VIII. ( online )