North American Fruit Explorers mailing list at ibiblio

[Pat Meadows <pat@containerseeds.com>]

On Sun, 01 May 2005 23:45:57 +0000, you wrote:

>WI p.ivy doesn't mind cold winters, not much bothered by dry soil either.  I 
>don't recall seeing it on the driest sand, nor in marshes, otherwise "it's 
>everywhere".  Could elevation really be the limiting factor?  Seeds are 
>moved by birds; are they very strict about elevation?
>

I found this:

-----------
Minimum temperature averages 41.6 degrees Fahrenheit (5.3
deg C) in the north and a maximum average of 66.2 degrees
Fahrenheit (19 deg C) in the west [54,128].

http://www.fs.fed.us/database/feis/plants/vine/toxrad/botanical_and_ecological_characteristics.html

------------

I think that means minimum average temperature for the
entire year (it doesn't specify otherwise).  I don't know
our (Tioga County, PA) average temperature, so that doesn't
help much.

>From the same URL:

-------
Topography is flatland to rolling hills [33,56,116].
Poison-ivy also occurs on steeper slopes in the southwestern
states [71].  Upper elevation limits for poison-ivy growth
are 7,080 feet (2,158 m) in New Mexico and 1,700 feet (518
m) in Tennessee [35,94].
-----------

We are at about 1700 feet in Northern Pennsylvania, and no
doubt considerably colder in winter than the same altitude
in Tennessee.  So I'm guessing it's minimum winter
temperature.  

I suppose it could be late frosts too:  we often have
killing frosts here in mid-June.  If poison ivy blooms
early, maybe the blossoms are killed by frost.  Our lilac
bush has that problem and so far has only bloomed two of the
four years we've lived here.  Peach and apricot trees will
not fruit here because of the late frosts.

Pat