Sub-division :- Algae

Class :- Chlorophyceae

Order :- Oedogoniales

Family :- Oedogoniaceae

Genus :- Oedogonium

Oedogonium. A filament.



  • Thallus is multicellular, filamentous and unbranched.
  • A filament is differentiated into three types of cells according to their position :
    1. basal
    2. intercalary and
    3. apical. 
  • The basal cell of a filament functions as a holdfast. The lower part of the holdfast is either disc-like or finger-shaped. The upper part is mostly broad and rounded. The basal part of the cell generally lacks green pigment and, therefore, is non-green unlike other cells of the filament. 
  • A cell at the tip of the filament is known as’ apical cell. It is rounded at its free surface. 
  • The cells present between basal and the apical cells are intercalary cells. These show typical cell structure.
  • The typical cell is cylindrical.
  • Cell wall is thick and three layered.
  • Inner to cell wall is a reticulate chloroplast that runs parallel to the long axis of the cell. Many pyrenoids are present in the chloroplast.
  • The cell is uninucleate. The nucleus is situated near the cell wall and is held by thin and delicate cytoplasmic strands. 
  • Mature and old cells show ‘cap cells’ at their upper end. These are characteristic of the members of Oedogoniales.

Oedogonium. Filament showing a mature oogonium.



  • Oogonia are intercalary or terminal in position. 
  • Oogonium may be solitary or occur in a row of 2-3 or even more.
  • Oogonium generally shows one or more cap cells at its upper end, indicating its development from a comparatively older cell. 
  • It is mostly spherical or oval in shape and larger than a vegetative cell. 
  • At the base of each oogonium lies a small and flat daughter cell, known as supporting or suffultory cell. 
  • Oogonium encloses a single large ovum.
  • The wall of the oogonium has a small pore on one side, Known as receptive pore. 
  • Just opposite the receptive pore, protoplast of the oogonium has a hyaline area-receptive spot. 
  • Uninucleate protoplast is rich in reserve food.

Oedogonium. Oogonium with two dwarf males attached to it. (Nannandrous species)



  • Antheridia are mostly intercalary in position. 
  • Numerous antheridia form a long chain being arranged in a series.
  • An antheridium is a small and flat cell.
  • Each antheridium has two nuclei lying side by side, surrounded by dense cytoplasmic contents. Each of such protoplasmic groups later on metamorphoses into a multiflagellate antherozoid.

Oedogonium. Part of a filament showing a chain of antheridia (Macrandrous species).



  • The dwarf male (or nannandrium) is characteristic of nannandrous species.
  • The dwarf male is produced by the germination of androspore. 
  • Androspores are formed inside the androsporangia. 
  • Androsporangia form a long chain of small and flat cells in intercalary position in the filament.
  • Each androsporangium develops a single multiflagellate androspore (in contrast, per antheridium two antherozoids are produced). 
  • Androspore germinates to produce a dwarf male or nannandrium which remains attached either to the wall of the oogonium or to the suffultory cell. 
  • A dwarf male is made of a stalk cell and a terminal row of 2-3 cells. 
  • Stalk cell is at the base by which the dwarf male is attached to the filament. It has a disclike or finger-like structure at its base.
  • The terminal row has 2-3 small, flat and narrow antheridia. 
  • Each anteridium has two multiflagellate antherozoids.

zygote of oedogonium


  • Zygote is thick-walled post-fertilization structure. The wall is generally three layered.
  • The layer outside the innermost may be smooth, ornamented or verrucose. 
  • Zygote develops red colour due to the accumulation of reserve food in the form of reddish oil drops.


  1. Sub-division– Algae
    1. Presence of a simple thallus.
    2. Chlorophyll present
    3. Cell wall made of cellulose.
  2. ClassChlorophyceae
    1. Presence of a definite nucleus
    2. Chloroplast present. grass green colour
    3. Presence of starch
    4. Reproductive structure motile and flagella equal in length.
  3. OrderOedogoniales
    1. Cells uninucleate, filaments branched or unbrahched,
    2. Cell division forming ‘caps’.
    3. Chloroplast reticulate
    4. Zoospores and antherozoids bear a whorl of flagella
    5. Production of dwarf males.
  4. Family Oedogoniaceae  (A single family) 
  5. Genus Oedogonium
    1. Filaments unbranched
    2. Cells cylindrical
    3. Holdfast well developed.



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