|MadSci Network: Botany|
The question might be better posed as: Why do some plants need less light than others? Plants have adapted to a wide range of light intensity, quality, and quantity. Some plants grow in areas that NEVER receive direct sunlight; others adapted to growing in deserts where they almost always receive intense sunlight; others grow near the poles where they might not receive direct sunlight more than 3 months/ year; others grow in understory [beneath other plants so the light they get is 'passed through' by other plants]. All plants need sunlight to carry on photosynthesis. Some plants are parasites that lack chlorophyll but depend on other plants that carry on photosynthesis for their 'food'. Adaptations in the plant's chloroplasts [light gathering organs for photosynthesis] make it possible for some plants to reduce carbon dioxide to make sugars and acids under lower light conditions than other plants and for some desert plants to do this at night when temperatures are lower and the risk of water loss is less.
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