Yellow-green algae

Yellow-green algae are the Xanthophyceae (xanthophytes).
They are a group of heterokont algae. Most live in fresh water, but some live 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 "c", β-carotene, and the carotenoid diadinoxanthin.
Unlike other heterokonts, their chloroplasts do not have fucoxanthin, which accounts for their lighter colour. Xanthophyte cell walls are made of cellulose and hemicellulose. They may be the closest relatives of the brown algae.