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Sunday, October 7, 2012

Pine cones-Are They Rain Predictors?

We continue forth learning about plant parts, functions, adaptions, and how we depend on plants to live.  On Friday we closely examined a pine cone and asked a variety of questions about them-where do they come from, why is it shaped like it is, when do you see a pine cone on a tree?  why is it sticky?   I asked them can they predict if it is going to rain?  I told my students I heard that they can, so we set up an experiment to see if my friend was correct.
First, we examine the pine cones with a magnifying class and discussed the features we observed.  Next we dropped our pine cones in a bucket of water. Then we watched!  Within minutes the pine cones had closed!  WHY?  We pulled or pine cones out of the water and they had all completely shut! 
I told them that pine cones tend to close when it is going to rain or has rained!  Thus, my friend is right...they are helpers to assist us in knowing if has rained or is going to rain.  But why do they close?  Furthermore, why are they open when it is dry outside?  We discussed how when they are open, this is the best time for the pine cone to release-disperse its seeds!  When it is wet, they shut because the conditions are less favorable.  Furthermore, they also open when it is dry because there outer 1/2s shrink more than their inner 1/2s, thus pulling away from the inner core.  When wet, the scales swell shut.  By the way, did you know there are female and male pine cones?  That's a seed of trivia for you!

Just dropped into the water!

After a few minutes in the water!

                                               Pine cone after being in the water for a few minutes!

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