border debates

Thu, 25 Mar 2010 21:28:25 PDT
I think the hisrotical geology and climate also affected it.

The high lands in the tropical america may help some species to move. the 
border is a filter.

And why not is the flora of tropical america stops at Mexco -USA border? 
Because we are in a warming Interglacial.


----- Original Message -----
From: Alani Davis <>
To: Pacific Bulb Society <>
Date: Thu, 25 Mar 2010 17:22:23 -0400
Subject: [pbs] border debates

> "The Flora of North America seems to stop at the Mexico-USA border.
> Where are all our experts when you need one?"
> Which part of the North American flora stops at the Mexican United States?
> There are many genera that bridge that artificial line. Oaks, pines, 
> magnolias, Mahonia, all occur on both sides and in some cases the same
> species and there are plenty of others that don't range widely in the
> northern United States but occur throughout the southeast and southwest 
> If I have the correct greatest diversity of Pinus and Quercus species in 
> world is found in Mexico. Another interesting twist, the cycad genus,
> *Ceratozamia
> *represented by several species in Mexico, Guatemala, and Belize is
> represent in fossil form from Alaska. Seems to me there is a fair amount 
> moving around.
> Alani Davis
> -- 
> Alani
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