Images of desmids from the genus Scenedesmus

  by Mike Morgan, UK

Some spun down silt from the bottom of a pond showed a number of species of Scenedesmus.

Scenedesmus: This is a member of the Phylum Chlorophyta, in the Order Chlorococcales and Family Scendesmaceae It occurs as flat colonies of 2, 4 or 8 cells arranged in a row, though there may be a single row of 12 cells. The cells are oval, fusiform, or crescent-shaped according to the species. In some there are 2 forms of cells in the same colony (coenobe), the individuals at the outside of the row often being lunate, rather than oval, and different in the form of spines Most species have spines at the corners of the colonies. Each cell has a parietal plate-like chloroplast and usually one pyrenoid (a protein granule and site of starch formation). The cells are 5-30 m m long. The normal method of reproduction is asexual by autocoenobium. There are numerous species and varieties of this genus; perhaps the most common species is S. quadricauda. Growth is large in nutrient rich waters.

 Comments to the author Mike Morgan are welcomed.

Left: Scenedesmus incrassatulus. Right: Scenedesmus opoliensis.

Left: Scenedesmus obliquus. Right: Scenedesmus quadricauda.

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