COLEOCHAETE

CLASSIFICATION OF COLEOCHAETE​

Sub-division :- Algae

Class :- Chlorophyceae

Order :-  Chaetophorales

Family :- Coleochaetaceae

Genus :- Coleochaete

THALLUS OF COLEOCHAETE​

• 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.

REPRODUCTIVE STRUCTURES OF COLEOCHAETE​

• 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.

IDENTIFICATION

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 –  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.