| Yellow-green algae | |
|---|---|
| Botydium granulatum | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Chromalveolata |
| Phylum: | Heterokontophyta |
| Class: | Xanthophyceae Allorge ex Fritsch |
Yellow-green algae or xanthophytes are an important group of heterokont algae. Most live in freshwater, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Xanthophyte chloroplasts contain the photosynthetic pigments Chlorophyll a, Chlorophyll b, β-Carotene, and the carotenoid diadinoxanthin.[1] Unlike other heterokonts, their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. Its storage polysaccharide is chrysolaminarin.[1] Xanthophyte cell walls are produced of cellulose and hemicellulose.[1] They appear to be the closest relatives of the brown algae.
The Xanthophyceae have been divided into the following four orders in some classification systems:
Recent ultrastructural and molecular phylogenetic DNA (nuclear and plastid) research shows that the Mischococcales might be paraphyletic, and the Tribonematales and Botrydiales polyphyletic, and suggests two orders at most be used until the relationships within the division are sorted.[3]
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