LEAF ABSCISSION

Jon Monroe MONROEJD at VAX1.ACS.JMU.EDU
Wed Nov 29 21:36:40 EST 1995


> At 11:23 AM 11/20/95 -0800, David Haas wrote:
> >A botany student of mine came up with an interesting observation
> >this AM.  As he was raking leaves over the week end (mostly pecan) he noticed
> >that the leaflets appeared to have abscissed in a manner
> >similar to the petiole.  It seems that I also made the same
> >observation years ago but never gave it much thought.  Now after
> >thinking about it I am wondering if this happens in all or most
> >compound leaves.   Are there any trees where the leaflets fall before
> >the leaves?    Have any of you noticed this?  Comments


I just remembered a story told by Herb Wagner (U of Michigan) relating to this
thread.  It seems that some caterpillars that form cocoons on several tree
species can tell the difference between simple and compound leaves.  For the
cocoon to remain in the tree after abscision the caterpillar must attach the
leaf to the stem.  For a simple leaf this would be one "turn" away but for a
compound leaf the same species of caterpillar makes two turns so as not to fall
when the leaflet and rachis are shed!  This doesn't answer the question on
the temporal order of abscision, but it is one of my favorite stories...

Jon

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