The Peepal tree (Ficus religiosa) is one tree that can take in carbon dioxide at night. This is due to its use of Crassulacean Acid Metabolism (CAM) photosynthesis. However, it's crucial to understand that no tree releases significant amounts of oxygen at night.
Understanding Photosynthesis and Respiration
Most plants, including trees, perform photosynthesis during the day, using sunlight to convert carbon dioxide and water into glucose (sugar) and oxygen. At night, they undergo respiration, using oxygen and releasing carbon dioxide. The oxygen production during photosynthesis significantly outweighs the oxygen consumption during respiration during the daytime for most plants.
CAM Photosynthesis: A Unique Adaptation
Plants using CAM photosynthesis, like the Peepal tree, have a different approach. They open their stomata (tiny pores on leaves) at night to take in carbon dioxide, storing it as an acid. During the day, they close their stomata to conserve water and use the stored carbon dioxide for photosynthesis. While this process allows them to reduce water loss in arid environments, it doesn't result in a net release of oxygen at night. The oxygen produced is used internally during the night for cellular respiration.
Other Plants Mentioned in the References
Several references mention other plants that are claimed to release oxygen at night, such as the Neem tree and various houseplants. However, these claims lack scientific backing. The net result for almost all plants is an uptake of oxygen and release of carbon dioxide during the nighttime hours.
Clarification: Oxygen Production vs. Net Oxygen Release
It's important to distinguish between oxygen production and net oxygen release. While some metabolic processes within the plant might produce oxygen at night, this production is minimal compared to consumption and the plant will exhibit a net uptake of oxygen and a release of carbon dioxide.
