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PLANTS AND MAN 



ing (from June to November) and navels, for a winter crop. The 

 NAVEL orange has a thick skin and excellent meaty pulp; it is a 

 seedless variety introduced into the United States from Brazil by 

 the Department of Agriculture. Its name is due to the formation 

 of a smaller secondary fruit at one end, leaving a navel-like 

 depression. Of two original trees sent to Riverside, California, in 

 1873, one is still standing, guarded by an iron fence. From these, 

 some nine million descendants are now growing in California 

 alone, producing (in 1937) fourteen million boxes of fruit. 



Fig. 142. — Grapefruit is the largest of the citrus fruits. 



Oranges are also an important crop in many other countries 

 with sub-tropical climates. Leading the list are Spain, Italy, 

 Palestine, South Africa, Brazil and Japan. 



Grapefruit trees grow to a larger size than oranges, reach- 

 ing forty feet in height; under cultivation they are kept as low- 

 growing as possible, however, to make picking the crop easier. 

 Grapefruit (fig. 142) is the largest of the citrus fruits, sometimes 

 reaching a diameter of six inches and a weight of ten pounds. 

 Their popular name comes from the fact that they grow in 

 clusters on the branches. The flesh is slightly more acid and bitter 

 than that of oranges. No fruit has a more uncertain birthplace; 



