Ted, The orange trees only popular in south of China where people speak Cantonese.Like Guandong,Guangxi,Hong Kong, Even Singapore...
Because the pronunciation of orange in Cantonese is the same as "lucky",And the color is gold, it also has another name" fortune tree" .So they like to buy little orange trees to decorate their house. It makes the house full of happy festival atmosphere.It is infelicitous to eat the oranges in the tree.