Question
Hi Tom,
You wrote in a previous response that you have a Mimosa Tree in your yard. I know it is not the same as a TickleMe Plant (Mimosa pudica). What I was wondering about is if the young sprouts close their leaves and lower their branches like the TickleMe Plant does when it is touched. The TickleMe Plant is the most interactive plant I know of in the world. I do know the Mimosa Tree and the TickleMe Plant both close their leaves at night  "sleep". I have heard rumors that young Mimosa Tree seedlings may do the same, but I have never had anyone confirm that. I hope you can solve this mystery for me.
Thank you.

Answer
Hi Sara,
Thanx for your question.  I cannot say that I have ever seen a Mimosa (Albizia julibrissin) close up upon being touched like I have experienced with the Tickle Me or Sensitive plant (Mimosa pudica).  I have a mimosa tree growing in my backyard and I cannot recall having it's leaves close up upon being touched.  I noticed, as you stated, that the leaves will fold together come nightfall.  Some references I have read indicate that A. julibrissin's leaves fold together upon touch.

The Missouri Botanical Gardens says that the leaves close up upon being touched.  Because they are horticultural experts, I would gladly go with their information.  See link below.

http://www.mobot.org/gardinghelp/plantfinder/Plant.asp?code=A848

I hope this helps.
Tom