Here in Africa there are a number of species that close up their leaves in response to touch. You can see an example of a similar plant on Wikipedia, but it says that one is from South America. I don't know the names of any of the African ones, but I have seen them.
http://en.wikipedia.org/wiki/Rapid_plant_movement
Edit: I may also have seen the South American one, but I am fairly sure there are some native plants that do the same, albeit less rapidly.
Originally posted by Paul Dirac II Is there any expectation that evolution will create plants with a nervous system and some degree of logic processing?
Plants do have something similar to a nervous system already, and because of this they can respond to stimuli to varying degrees (such as turning their leaves towards the sunlight). I don't see why they couldn't in time evolve something like a brain (which at it's most rudimentary is really just a bundle of nerves anyway). A brain comes at a cost though, so it would have to be useful in plant survival, or it would be selected against. You can imagine that a plant that could determine if a given insect would be good for it or not can change its appearance to either attract or repel an insect at any given time, could make good use of a brain. But evolution is not a directed process, so whether or not this will happen is impossible to predict.
Originally posted by C Hess Plants do have something similar to a nervous system already,....
I do not think 'nervous system' would be the right term though. Plants do engage in various sorts of messaging both around the plants body and also between the plant and other plants or animals.
But animals do this too in many different ways for example using hormones or pheromones. Yet we would not really call hormones part of the nervous system. The nervous system is an organ whose primary functions are sense, communication and in many cases, thought.
Originally posted by twhitehead I do not think 'nervous system' would be the right term though. Plants do engage in various sorts of messaging both around the plants body and also between the plant and other plants or animals.
But animals do this too in many different ways for example using hormones or pheromones. Yet we would not really call hormones part of the nervous system. The ne ...[text shortened]... system is an organ whose primary functions are sense, communication and in many cases, thought.
I did write: "something similar to a nervous system", for a reason. There are cells in plants that are similar to nerve cells in animals. They generate electrical signals that propagate through the plant, but it's not clear exactly how these are used in plants. I would say that what makes something a nervous system is simply the ability to sense (to react to stimuli), it doesn't need to include a brain (a nerve net is an example of a brainless nervous system).
On the Na Pali coastal trail of Kauai I was told that snapping sound came "from a walking tree."
I gather the roots can detach from the ground on one side of the tree while entrenching themselves on the opposite side. I have not researched into how or why this happens.
Originally posted by C Hess I did write: "something similar to a nervous system", for a reason.
Yes, I wasn't disputing your post, just trying to clarify.
There are cells in plants that are similar to nerve cells in animals. They generate electrical signals that propagate through the plant, but it's not clear exactly how these are used in plants. OK, I didn't realize that. Can you give any references? That is not how they turn towards sunlight as far as I know.
I would say that what makes something a nervous system is simply the ability to sense (to react to stimuli), it doesn't need to include a brain (a nerve net is an example of a brainless nervous system). So would you call the process of getting a sun tan indicative of a nervous system? What about hormones?
Originally posted by twhitehead Can you give any references? That is not how they turn towards sunlight as far as I know.
In my first post I was talking about a sensory/response system in general (and heliotropism would be an example). In my second post I bring up electrical signals in response to your post, only to point out that there are cells that resembles neurons in plants, though it's not understood exactly how they're used.
Originally posted by twhitehead So would you call the process of getting a sun tan indicative of a nervous system? What about hormones?
To be honest, I'm not exactly sure where I would draw the line. 😕
In animals, the nervous system is very specifically built by neurons that react very quickly. Perhaps the reaction time matters? But for a plant, turning leaves towards the sun is a relatively fast response. To be honest, you've got me stumped. I'd have to think about this. Thank you. 🙂
Originally posted by C Hess But for a plant, turning leaves towards the sun is a relatively fast response.
There are plants that follow the sun by time of day, and others that just generally grow towards the sun. There is also the tendency to grow vertically ('sensing' gravity), or in the case of climbing plants, to move in a spiral.
Plants do take account of their environment and take adaptive action, sometimes in surprising ways. They do not have a brain as such but there is a section of the plant just at the top of its roots which is clearly responsible for organising the way the roots and leaves develop for example.
More anecdotally, my wife and I keep quite a lot of house-plants and have done for some decades. Stuff goes on all the time and they need a lot of management. There are quite a few that we agree are troublemakers, and need a lot of attention to curtail their annoying habits. The most obvious example is the way they chase after sunlight.
plants behaving like animals
06 Feb '15 19:45
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