442 GENERAL MORPHOLOGY OF PLANTS 



Another new fruit, tangero, is a cross between the tangerine 

 and grape fruit, in which the qualities of the two fruits are 

 blended. 



595. Oranges. The varieties of oranges originated from one 

 species (Citrus aurantium), the principal forms found in the 

 market being sweet, while some forms are bitter. In the United 

 States they are cultivated in central and southern Florida, in 

 California and in the delta region of the Mississippi. The seed- 

 less naval oranges grown in California were introduced in 1870 

 from Brazil where they originated as a seedling variety. The 

 mandarins or " kid glove oranges " belong to a closely related 

 species (Citrus nobilis). Some are small and of a light orange 

 color, while others called tangerines are dark orange or red and 

 are preferred in the market to the others. 



596. Grape fruits. The grape fruits were derived from a 

 species (Citrus decumana) native in the Malayan and Polynesian 

 Islands. Many of the varieties have originated in Florida. The 

 fruit is rounded in form, and was earlier known as pomelo, and 

 sometimes called shaddock, while the real shaddock is a different 

 variety, pear-shaped and little used. Grape fruit is extensively 

 cultivated in India, Florida and California. 



597. Lemons. The lemons (Citrus medico) are cultivated to 

 some extent in Florida and California, but they are more easily 

 injured by cold, and our chief supply comes from southeastern 

 Europe (Italy, Spain and Portugal). The lime is a variety of the 

 lemon, with acid, bitter fruit from which lime juice is obtained. 



598. The maple family (Aceraceae) has inconspicuous flowers 

 and the fruit is called a key fruit or samara. Several of the 

 maples are valuable timber trees. The hard or rock maple 

 (Acer saccharum) is also known as sugar maple, its sap yield- 

 ing the maple sugar of commerce. When the wood is full of 

 little knots, the grain of the lumber is very beautiful because of 

 numerous concentric rings. It is then known as " bird's-eye " 

 maple, and is much prized for cabinet work. The black sugar 

 maple is A. nigrum. The soft maple (A. saccharinum) yields 

 smaller quantities of sap. These and several other maples, as 



