imperfect leaf drop

PROFDHW at aol.com PROFDHW at aol.com
Wed Mar 5 21:12:46 EST 1997


In a message dated 3/3/97 6:41:38 PM, Florent Lemieux wrote:

>My question is : Why red oak and young american beech keep theirs leaves 
>in the winter ( I live near Montreal at the north of the U.S. )Somebody 
>told me it's because oak and beech have an imperfect metabolism at the 
>autumn.

This one keeps making the rounds. I have definitely seen a thread on the
imperfectly deciduous nature of oaks before. The truth is, not all
characteristics are selected for. Some things just wind up being the way they
are by a combination of historic contingency and chance.

In the case of oaks, the salient fact is that the VAST majority of oaks are
evergreen, like the live oak of the Southeast U.S. Most grow in Mexico (the
probable point of origin for oaks) and Central America. The paltry few we
know in the Northern U.S. and Canada are imperfectly deciduous because of the
historic contingency of having been recently descended (in geologic and
evolutionary time) from evergreen ancestors and the fact that the leaves hangi
ng on probably does no harm. You can invent possible selective advantages
till the cows come home but the real truth is probably far less interesting.

Dave Williams
Science Division
Anne Arundel Community College
Arnold, MD 21012
Email: profdhw at aol.com
Vmail: 410-541-2265



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