On 21 Feb 2003 18:03:14 GMT, (Nick Maclaren)
wrote:


More seriously, I agree that the vast proportion of the agricultural
crops are not herbaceous, but they are not woody either, and the
average extreme minimum is quite inappropriate. There are many,
FAR better, measures for those, INCLUDING simple latitude!

Not really. If you look at a weather map of North America with
the temperature bands colored (or the USDA zone map, for that
matter!), you will see that they are *not* oriented east-west.
Indeed, on the left coast, the bands run north-south rather than
east-west. And in the south east, they run in a large curve that
aproximately parallels the coast from Texas to New England.

Judging from remarks in Donald Wyman's "Shrubs and Vines for
American Gardens", these zone maps were devised specifically for
ormnamental trees and shrubs. I was wrong in thinking that they
were devised for fruit trees. But they were definitely intended
for *woody* material, not herbaceous plants.

Wyman distinguishes the zone map devised at the Arnold Arboretum
from that devised by the USDA. And, might I add, that his words
imply that the USDA map was actually devised by the American
Horticultural Society and only published by the USDA. Your
disdain for it might not be too far off the mark after all.

--
Rodger Whitlock
Victoria, British Columbia, Canada