Why do plants close their leaves at night?
Very few people know why some plants close their leaves at night! Are you one of them.
Plants close their leaves at night because carbon dioxide and water are exchanged at night through the pores in plant leaves. A plant cannot absorb carbon dioxide without allowing water vapor to escape. So in order to prevent from excessive water loss, leaves tends to close at night when photosynthesis is not happening.
These are called ‘Nyctinasty’ plants which close their leaves and petals at night. Nyctinasty is the circadian rhythmic movement associated with light and temperature, making plants open their leaves and closing it biochemically with respect to light, as there are light receptors that govern the whole process.
Though some plants close their leaves and flower petals at night but few have reversed the process to their advantage. Desert plants and alpine can’t risk losing water during the day because of the excessive heat and high temperature, so they close the leaves inwards and protect themselves from the extremely dry surroundings.
To avoid drying out in these conditions, some plants have adapted to open their leaves at night, taking in lower amounts of carbon dioxide but also lowering the risk of drying out.