Climatology of the Citrus. 
By Dr. Wm. C. Richardson. 
Mr. President 3 Ladies and Gentlemen: 
The subject of climate has in all ages 
and all countries furnished a vast and 
highly important field for the considera¬ 
tion of the horticulturist. 
This is especially true of those engaged 
in citrus fruit culture, for it is a thor¬ 
oughly demonstrated fact that the orange 
is limited in its profitable commercial 
production to certain well defined climatic 
zones. 
The study of airs, waters, places and 
soils may fairly be said to embrace chiefly 
chat which is included in the climatology 
of a locality or territory. On the north¬ 
ern hemisphere the isothermal line of 
seventy may perhaps be said to be the 
centre of * the orange growing districts, 
and the isotherms of sixty and eighty 
practically, though not exclusively, the 
limits. The isotherm of seventy is not 
confined to latitude but extends, in belt¬ 
ing the earth, north and south more than 
ten degrees and may be said to range be¬ 
tween the twenty-fifth and thirty-fifth 
parallels. Within this belt are found the 
orange-growing districts of California, 
Mexico, Louisiana, Florida, Spain, Mo¬ 
rocco, Algiers, Italy, Egypt and Asia 
Minor. 
These are not the only countries in 
which the orange thrives, as there are 
many other places in the transitional 
zones, both north and south, in which it 
may be found doing fairly well, but they 
include nearly all the districts that are 
chief factors in the commercial produc¬ 
tion of this fruit. 
The orange does not attain its great¬ 
est perfection or productiveness in tropic 
heat and can stand little or no freezing 
cold, hence any place where the tempera¬ 
ture ranges for any length of time below 
twenty or above one hundred is not a 
suitable climate for its culture. In South¬ 
ern Europe, Northern Africa, Western 
Asia and in California the cold is greater 
than in Florida, but is more evenly dis¬ 
tributed and continuous. In Spain, 
Southern France and Northern Italy or¬ 
ange groves are often covered with snow. 
In these countries, and in California as 
well, temperatures ranging as low as 
seventeen or eighteen degrees Fahrenheit 
are not infrequent and result in no seri¬ 
ous harm to orange trees. In Florida, 
owing to more warm davs. such extremes 
would be disastrous. Continuous cold 
weather hardens the tr^es, but alternate 
warm and cold periods do great damage. 
Under the head of water in relation 
to orange culture ■.{ may be said that it 
is a necessity in liberal quantities. 
As to location, it is a fact worthy of 
note that the most thriving districts are 
clustered around large bodies of water, 
as the Pacific, Mexican Gulf and Medi¬ 
terranean Coasts. 
The most extensive orange districts of 
Mexico are perhaps an exception to this 
and are found on the table lands, at ele¬ 
vations of from three to five thousand 
