202 PLANTS AND MAN 



grown best on well drained soil adjacent to the sea in a climate 

 where the temperature ranges between 24 and 120 degrees 

 Fahrenheit. Ripe fruit is produced continuously throughout the 

 year, and in some cases as with the lemon, trees produce flowers, 

 immature fruit and ripe fruit at the same time. The United 

 States ranks first in citrus fruit crops, with the Mediterranean 

 countries (Portugal, Spain, Italy, Palestine) second in impor- 

 tance — even though citrus fruit culture is one of our most recent 

 industries. 



The ORANGE, hardiest niember of the genus, is indigenous to 

 the Indo-Chinese region, where two distinct species occur — the 

 sour orange and the sweet orange. The sour orange has a reddish 

 fruit with thick skin and sour pulp; this was the first orange to be 

 introduced into Europe — after centuries of cultivation in China 

 — in about the twelfth century. Orange trees were brought to 

 Persia by the Arabs, then later to Syria, northern Africa and 

 Spain. Sour oranges were also the first to be introduced into the 

 New World, being brought to Florida by the Spaniards. Native 

 Indian tribes spread this species so that groves of "wild" oranges 

 are found around various lakes and rivers in that state. The chief 

 use of sour orange trees is a stock on which to graft the less hardy 

 sweet orange. The sour oranges, known as Seville oranges, are 

 grown in Spain and the fruit shipped to England and Scotland 

 where it is made into marmalade. 



The common sweet orange tree is of moderate size, with a 

 dense rounded head of dark green foliage and with fruit (fig. 141) 

 of a golden-yellow color. Oranges contain 5-10% sugars in solu- 

 tion, 2% citric acid and an abundance of vitamin C. In recent 

 years they have become one of the most popular fresh fruits for 

 year-round consumption. Sweet oranges were brought to Europe 

 from India sometime before the fourteenth century; they were 

 introduced into Florida before the English occupation. A sweet 

 orange grove, dating to 1823, is said to be the parent of all the 

 Indian River oranges. The cultivation of sweet oranges began 

 along the shores of lakes and rivers where the sour orange groves, 

 already established, were used as stock on which the sweet orange 

 was grafted. In 1894 the Florida output was four million oranges. 

 Then came an excessively cold winter and fungus diseases which 



