Is there such a thing as orange trees?

Yes, there are such things as orange trees.

Information about the evergreen trees, originally from Southeast Asia, that bear the many types of fruit we call Oranges, is well-covered in the link below.

There are also trees which have leaves with orange coloring all year, and deciduous trees which have leaves that turn orange, among other colors, as the weather cools and the leaves become ready to drop ahead of winter.