53. Aurantieae.—Sub-order of Rutaceae.—The Orange Family.
The trees and shrubs which compose this sub-order of Rutaceae are distinguished from others of the order merely by the character of the fruit. In the Aurantieae the fruit is an indehiscent, juicy, berry-like fruit, botanically known as hesperidium (lemon, orange, and lime), having a leathery rind, containing numerous oil-glands. The capsular fruit of the rueworts proper is usually dehiscent. The leaves and fruit of both sub-orders abound in minute receptacles of volatile oil. These attain their maximum development in the rind of the orange, lemon, etc. (see Figs. 150, 151, 152).