General characteristics of Xanthophyceae
- Members of Xanthophyceae are commonly fresh water (Tribonema) and most of them are free floating.
- Plant body is unicellular (Heterochloris) or multicellular.
- The multicellular bodies also exhibit various forms like: Palmelloid (Chlorogloea), dendroid (Mischococcus), coccoid (Chlorobotrys), rhizopodial (Stipitococcus).
- Cells are eukaryotic with silica and pectin in cell wall.
- Chief pigment are Chl A and Chl E, beta carotene, neoxanthin, and violoxanthin.
- Reserve food material includes chrysolaminarin and oils, starch and pyrenoids absent.
- Cell wall is often absent, but when present, it contains more pectic compounds than the member of chlorophyceae.
- Occasionally cellulose is also present.
- The motile forms bears usually two flagella but rarely one.
- The chromatophores are discoid in shape.
- Sexual reproduction is isogamous, anisogamous, or oogamous.
- Zoospore formation is common
- Male gamete are flagellate
- Flagella are heterokont unequal.
- Life cycle are mostly haplontic.
- Plant reproduce commonly by vegetative and asexual means.
- Vegetative reproduction take place by cell division.
- Asexual reproduction by zoospore, aplanospores, or akinetes.
- Sexual reprodcuction though rare, may be isogamous, anisogamous, or oogamous. Isogamy is common. Both iso and anisogamy are found in Botridium.
Examples: Vaucheria, Tribonema, Botrydium
Xanthophyceae (Yellow Green Algae)