Question: Northern Palm Limit

Harold Slater hslater at r-node.io.org
Tue Dec 13 20:05:32 EST 1994


Brent Taylor VE1JH (btaylor at nbnet.nb.ca) wrote:

: The eastern North American portion of the Northern Limit of Palms, in part, 
: passes just north of Houston and San Antonio heading eastward through 
: northern Louisiana, Mississippi, Alabama and Georgia, then it turns north-
: eastward to cover most of South Carolina, eastern North Carolina and 
: eastern Virginia.  The line crosses Chesapeake Bay, the Tidewater area of 
: Virginia and leaves North America at about Lewes, Delaware...passing just 
: to the south of Cape May, New Jersey.  It passes just a few hundred miles 
: south of Long Island, curving east-north-eastward off Cape Cod, then 

: 1)  Is the "Northern Limit of Palms" an accepted climatological definition 
: or some historical line drawn by some long-dead explorer or scientist, or 
: is it an estimate of the Gulf Stream effects on vegetation?

I personally believe that climatological zone maps and vegetation
distribution should only be used as guidelines and not as hard and fast
rules. There are many instances where introduced species from other
continents have survived and thrived in latitudes where they shouldn't.
These of course can be attributed to mini/micro climates in lieu of
modifying factors (oceans, mountains etc) One good example of palms is the
Chinese Fan Palms. They grow quite happily in southern England and Ireland
due to the effect of the Gulf stream. They also grow well in a number of
private gardens on southern Vancouver Island. A line drawn as an indication
of the limit of palms would be very fuzzy and in flux from year to year.
I also think that many species of supposedly southern plants haven't
migrated farther north may be attributed to physical barriers and related
harsher climates. In a personal example: I have 8 species of cacti growing
outside happily here in southern Ontario. I know that one species is
locally native but why wouldn't the other species be found here even
sporadically.

Harold



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