388 ELEMENTARY STUDIES IN BOTANY 



A second important fruit-bearing family is the rue family 

 (Rutacea), whose genus Citrus includes oranges, lemons, 

 and grape-fruits. The genus is a native of Asia, but these 

 fruits are known everywhere. From the name of the genus, 

 this group of fruits is usually called the " citrous fruits." 



FIG. 62. Pear, showing a branch with flowers (A), a section of the flower, showing, 

 how the calyx and ovary grow together to form the fruit (B), and a section of the 

 fruit (C), showing the thickened calyx outside and the ovary or "core" within (indi- 

 cated by the dotted outline). After WOSSIDLO. 



These are all really berries with a leathery rind, a berry 

 being an ovary that becomes pulpy throughout (as currants, 

 gooseberries, grapes, tomatoes). 



A third notable fruit-bearing family is the vine family 

 (Vitaceffi), for it includes the grapes. The habit of these 

 woody climbers, with their tendrils, broad leaves, and clus- 

 teis of small but fragrant flowers, is probably familiar to all, 



