PERCENTAGE OF WORLDWIDE LAND AREA BY LATITUDE WHERE PALMS CAN GROW

Below is the percentage of land area around the world at each
latitude (within one degree) where palms can grow.  In borderline
cases, this includes places where at least one type of trunked
palm can grow without any added protection during the winter.  In
many cases at the higher latitudes, only one type of trunked palm
can survive outdoors--the Chinese windmill palm (Trachycarpus
fortunei)--though other species of Trachycarpus may be possible.  
The winters are milder in most of the Southern Hemisphere (except 
Antartica, of course!) than in the Northern Hemisphere because 
there is so much more ocean, so the percentage of landmass able 
to support palms there is much higher.  The numbers below are based 
on climate and may include a few areas where palms have not yet 
been attempted because people are unaware of their possibilities.  
Irrigation may be required in some areas!

In the tropics, the only areas that can not support palms (at least
with irrigation) is in high mountain areas.  In some cases, near
the equator, one must go very high in the mountains to escape palms
completely, as palms can grow at 12000 feet, or even locally higher, 
in some parts of the Andes.

Except for islands, oceanic areas do not count.  After all, palms
don't float too well (standing up, at least) in the ocean!

Latitude      Sample Places Near That Latitude     Percent Where
              (with or without palms)              Palms Can Grow 
60 degrees N  Oslo, St. Petersburg, Hudson Bay         0
55 degrees N  Copenhagen, Moscow, Labrador, Belfast    2
50 degrees N  English Channel, Prague, Winnipeg        3
45 degrees N  Portland (Or.), Montreal, Venice         7
40 degrees N  Denver, Philadelphia, Madrid, Beijing   13
35 degrees N  Santa Barbara, Memphis, Crete, Tokyo    28
30 degrees N  New Orleans, Jacksonville, Cairo        76
25 degrees N  Bahrain, Taipei, Key West, Nassau       98
20 degrees N  Mexico City, Haiti, Bombay, Hawaii      98
15 degrees N  Guatemala, Senegal, Bangkok, Manila     more than 99
10 degrees N  Costa Rica, Caracas, Trinidad, Ethiopia more than 99
5 degrees N   Bogota, Guyana, Cameroon, Maldives      more than 99
equator       Quito, Singapore, Mt. Kenya, Congo      more than 99
5 degrees S   Amazon Basin, Kinshasa, New Guinea      more than 99
10 degrees S  Lima, Comoros, Luanda, Bali             99
15 degrees S  Cuzco, Zambia, St. Helena               95
20 degrees S  Great Barrier Reef, Madagascar, Namibia 95
25 degrees S  Sao Paulo, Ayers Rock, Johannesburg     95
30 degrees S  Porto Alegre, Perth, Durban             95
35 degrees S  Buenos Aires, Cape Town, Sydney         94
40 degrees S  North Island of New Zealand, Valdivia   75
45 degrees S  South Island of New Zealand, Patagonia  80
50 degrees S  Lago Argentino, Falkland Islands         5 (marginally)
55 degrees S  Tierra del Fuego, South Georgia Is.      0