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. Class – Chlorophyceae
    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. Order – Oedogoniales
    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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