In this article we will discuss about the external morphology of coleochaete with its reproductive structure.
1. Plant body is thalloid, multicellular and of two types:
(a) Cushioned forms; (b) Discoid forms.
2. Cushioned forms, such as Coleochaetepulvinata show clear heterotrichous habit with a prostrate and an erect system (Fig. 23 A).
3. Erect system is very much branched and combine to form cushion.
4. Discoid forms, such as Coleochaetescutata and C. nitellarum, are represented mainly by prostrate system. Filaments in this system combine and form disc (Fig. 23), in which the cells remain arranged radially.
5. Thallus is surrounded by a sheath of mucilage in both the types.
6. All the species are characterized by the presence of some fine hairs called setae.
7. A basal sheath is present at the base of these hairs.
8. These hairs are not permanent structures.
9. Each cell is slightly elongated, uninucleate with parietal chloroplast.
10. Generally, only one pyrenoid is present in each cell.
1. Asexual reproduction is by biflagellate zoospores.
2. Zoospores are formed singly in zoosporangium.
3. Sexual reproduction is oogamous.
4. Antheridia are formed in the marginal cells and are present intermingled.
5. In each antheridium develops a single, biflagellate, colourlessantherozoid.
6. Oogonia also develop in terminal cells.
7. Each oogonium is a flask-shaped structure and contains a single egg.
8. Just after fertilization, some branches develop around the oospore, which completely surround it. It is called spermocarp.