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Chromoplasts (/"KROME-ə-plasts"/) are plastids, other than chloroplasts, that produce and store pigments. Found in flowers, leaves, roots and ripe fruits, they contain carotenoids (lipid-soluble pigments ranging from yellow to red in color), which lend color to the plant tissues containing them.
There are hundreds of carotenoids, each with its own characteristic color. Carotenoids are divided into two categories, those that contain oxygen (xanthophylls) and those that lack it (carotenes). Xanthophylls are yellow, while carotenes are orange.
In many fruits, chloroplasts convert to chromoplasts as fruits ripen so that there is a change in color from green to red, orange, or yellow. On the other hand, when leaves turn in the fall, it is due to the loss of the green color of chlorophyll which reveals the reds, oranges, and yellows that were there all along.
Very few animals can synthesize carotenoids, but, when ingested, these pigments do affect the color of various animal tissues such as egg yolk and body fat, lending them yellow and orange colorations.Julian Onderdonk, Fall Landscape:
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