A big part of the answer to whether or not plants have intelligence is how we define the term. They do sense and react to their environment, but do they choose the reaction or is it just an automatic response? I noticed an interesting phenomenon at my last house. We had two massive oaks on the property. One year the trees produced 3-4 times the normal amount of acorns. I found that many oaks in the area prouced a great abundance that year. I have read on the forums that plants may produce very little seed some years to starve out the animals that eat the seeds. Other years they will produce an abundance. Are the plants just reacting to climate cues? I would guess this is the case if the response is seen in all the plants in an area. We had had several years of drought. That may have caused it. I have noticed that for particular plants some years are good and others bad even though nothing seems different to me weatherwise. Plants do seem to have some level of perception and reaction. It looks like a very limited level of what we experience as humans.
Its funny this topic reminds me of the question do animals have feelings? As to plant having intelligence I'm not suprised if they do. Where I teach we do several plant experiments to see if plants will react, time and time again the plants do react. Plants that are given lots of positive attention do really well, and plants that are given negative attention do really badly. The interesting thing that we did last term, was to try treating the water differently without influencing the actual plant we gave "good vibes" to water then fed it to some plants, and gave " negative vibes" water going to other plants to see what happened. The ones with the negative water didn't do that well, and the positive exceded expectations. So the question could be asked where does the intelligence lie, with the plant or the water, or both? Carol Ja