COLEOCHAETE

CLASSIFICATION OF COLEOCHAETE​

Sub-division :- Algae

Class :- Chlorophyceae

Order :-  Chaetophorales

Family :- Coleochaetaceae

Genus :- Coleochaete

Coleochaete sp. Discoid thallus

THALLUS OF COLEOCHAETE​

COMMENTS :-

  • Thallus is multicellular and heterotrichous. 
  • It is either a disc-like structure ip. majority of the species (e.g. c. scutata) or cushionoid or filamentous (e.g. c. pulvinata) in others. 
  • It thallus is disc-like, the disc represents only the prostrate system while a few setae or hair, represent erect system.
  • Filamentous thallus exhibits typical heterotrichous habit with a branched prostrate system and a branched projecting (erect) system.
  • In both the cases a few cells possess a cytoplasmic outgrowth-setae. Setae are surrounded partly or wholly by a gelatinous sheath at the base. 
  • The thallus is distinctly enveloped by a gelatinous sheath or mucilage.
  • In discoid species cells of the thallus are joined end to end to form branches. These branches are laterally apposed to one another to form a pseudoparenchymatous disc.
  • Each cell is uninucleate. It has single, large, laminate and parietal chloroplast with a single pyrenoid. Rest of the cell is occupied by the cytoplasm.

Coleochaete sp. Cushionoid thallus

REPRODUCTIVE STRUCTURES OF COLEOCHAETE​

Coleochaete sp. Thallus bearing antheridia.

COMMENTS :-

  • Thalli may be homothallic or heterothallic. 
  • Sexual reproduction is oogamous.
  • Antheridia are generally borne at the tips in filamentous species and in the middle or peripheral region in the discoid species.
  • Anteridia appear as a group of small cells. 
  • Oogonia are also borne terminally in filamentous species and towards periphery in the discoid species. 
  • Oogonium is a flask-shaped structure with long tubular trichogyne. 
  • The fertilization results in the formation of a zygote which remains embedded inside the wall of the oogonium. It is a thick walled structure. 
  • Zygote known as spermocarp remains enveloped in a parenchymatous tissue formed by the development of neighbouring cells. It is conspicuously reddish-brown in colour. 
  • Spermocarp remains dormant for a long period.

Coleochaete sp. Thallus with sperrnocarps

IDENTIFICATION

  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. Order –  Chaetophorales
    1. Plant body heterotrichous
    2. Distinct prostrate and erect systems present.
    3. Presence of setae
  4. Family Coleochaetaceae
    1. Vegetative cells with long cytoplasmic hair (setae).
    2. Cells uninucleate
    3. Filaments branched
    4. Each cell with a single parietal and laminate chloroplast.
  5. Genus Coleochaete
    1. Plant body multicellular.
    2. Thallus parenchymatous
    3. Presence of spermocarp.

COLEOCHAETE

REFERENCES

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