Carotenes and xanthophylls are collectively called carotenoids. Carotenoids are yellow, brown orange or reddish pigments usually found in close association of chlorophylls in all photosynthesising cells. They occur in thylakoids and act as accessory pigments by absorbing light energy and transferring it to chlorophyll. They also pick up nascent oxygen and protect chlorophyll form photo-oxidation. Anthocyanins are reddish purple water soluble floavonoid pigments which have no active role in photosynthesis but act as a photoscreen and protect against photoinhibition.