Hello. I hope the question isn't too stupid. I have this curiosity, and got bored searching for the answer, so I thought I'd better ask: What exactly do they do at nighttime? Do they need "sleep"? They don't have a nervous system, no muscles to rest... Is there a detailed explanation somewhere on the net?
Nighttime is when plants "breathe" and "eat" for lack of better terms. All that lovely glucose that they store up during the day? Part of that gets used in their night processes, which actually entails oxygen consumption (just like mammals - they need oxygen to combust that sugar.) Some plants (I'm looking at you, bananas) continue their growth processes at night, while others are "dormant" in absence of light. I'm not sure if there's a detailed explanation out there, but a good starting point is "plant respiration."
An interesting fact I've found is that they "count" the hours of the night, so that they know if it's time to flower. (source) Some move towards East. And moonlight is unable to start off the photosynthesis (actually plants avoid it, to prevent it from resetting their internal clock). Thanks for the kind answer, lorax.
I'm surprised by the comment about moonlight "actually plants avoid it..." because I don't see HOW they could avoid it. Do they put their "heads" under their leaves? Surely any plant which gets sunlight in the daytime is going to get moonlight at night. Exposure to moonlight doesn't seem to stop Poinsettia hedges from flowering in California
By folding their leaves (source 1 source 2). I've seen this in plants with basal rosettes, and also in seedlings.
Good Morning Folks, Don't forget some plants do their 'hanky panky' at night. Good examples are those that bloom after sunset, like durian (Durio zibethinus) and some species of pigeon orchids. Peace Thean
The calvin cycle. simply put the plant creates carbohydrates for new growth and also a majority of root development occurs during lights off.
So, if I may summarize these erudite posts on the subject "What do plants do at night? I see that, in order, they do a little breathing & eat a snack. Check their watches, or automatic timers to see if they need to bloom. Then they move to the East (en-masse or on individual initiative I wonder?), apparently in order to avoid moonlight (how does that work??|) but also for other purposes not specified. This explains why I end up with of lot a weeds & volunteers along my Eastern fence line. I have always wondered - now I know. Some of them fold their leaves to avoid the moonlight as well. I wonder if there is a danger of them turning into "were-cabbages" or such? Then it's time for a bit of "hanky-panky". OK, that sounds reasonable - party-on! Some of them will then actually bloom, like Durian. OMG, that explains it! I thought I had a problem with my septic tank. Then, before dawn I assume, they get some exercise on their Calvin cycles. Guys, I am so grateful for this wonderful explanation. It has both saved me money (not having to pump my septic tank) & cleared up some existential questions that bothered my since I was a teenager, sporting my juvenile foliage. There seems to be some good material here for research projects as well. If anyone needs help in writing the grant applications, please let me know. That's a busy & fullfiiling schedule! No wonder so few of my plants are chlorotic or necrotic. They are taking better care of themselves than the average Canadian does. Lysichiton (what DO skunk Cabbages do at night anyway? Does it turn them bright yellow?)
scarumanga, I guess it's Krebs (according to Wikipedia, the Calvin cycle can't take place in the absence of light). Lysichiton, "my" is such a gross, unforgivable mistake.
Apologies Corni, but I am not sure which "my" is the issue, I seem to have included quite a few of them? BTW I loved your question. It was clear, obvious & as you can see, a bit of a head-scratcher to answer. There is actually a lot going on physiologically with "Circadian Rhythms in Plants" & responses that vary from species to species.
On search, "Circadian Rhythms in Plants" seems to yield exactly what I've been after. Thanks, Lysichiton!
I'm not 100% sure, but I think plants give off oxygen in the day, and then give off carbon dioxide at night and then when the sun comes back out they take in that carbon dioxide and give off oxygen.
Yep! That's the basics. Respiration, which produces the energy the plant needs to live from sugars within the plant, goes on 24 hours a day. This consumes Oxygen & produces Carbon Dioxide. Photosynthesis which uses light to make sugars from carbon dioxide & water, produces oxygen in the day time. This reduces the amount of carbon dioxide in the earth's atmopsphere. When the light is bright & the plant is growing, the amount of oxygen produced is more than the amount of carbon dioxide produced. The is a source of oxygen in the atmosphere & just about all the foodstuffs of animals, fungi & many bacteria. The sun is the giver of life. It's fascinating to me how much we depend on plants & how little most of us think about them. ...you wanna know more? This subject is complicated in it's details & varies among plant groups. A lifetime of study would still leave a lot of questions unanswered I think!
