Tribonema

Tribonema is a genus of filamentous xanthophyte algae (also known as yellow-green algae) belonging to the class Xanthophyceae and the order Tribonematales. These algae are commonly found in freshwater habitats, though some species can also tolerate brackish environments.

Tribonema filaments are unbranched and composed of cylindrical cells joined end-to-end. A key characteristic of Tribonema is the presence of distinctive H-shaped wall pieces, formed during cell division. These wall fragments persist within the filament, providing a diagnostic feature for identifying the genus.

Cells within the filament typically contain multiple discoid chloroplasts, which give the alga its yellow-green coloration. The pigments in these chloroplasts primarily include chlorophyll a, chlorophyll c, and various xanthophylls, such as vaucheriaxanthin.

Reproduction in Tribonema occurs both asexually and sexually. Asexual reproduction primarily takes place through the fragmentation of filaments, with each fragment capable of growing into a new filament. Sexual reproduction involves the formation of aplanospores, non-motile spores, within vegetative cells. These aplanospores are released and can develop into new filaments.

Tribonema species are ecologically significant as primary producers in aquatic ecosystems. They contribute to the base of the food web and can play a role in nutrient cycling. In some cases, excessive growth of Tribonema, like other algae, can lead to nuisance blooms, especially in nutrient-rich waters.

The taxonomy of Tribonema is based on morphological characteristics, including cell size, filament structure, and details of reproduction.