Making a railway layout means scaling down your train to replicate the large scale model. It also means that you will also scale down the environment or scenery to the same ratio as the train from the original size. Trees are commonly used to copy the real world. In making these miniature trees, real trees and plants are usually used. Australian gum is one of the known trees used.
Shrubs like the “Heavenly Bamboo” can be used also as a replacement for the Australian gum as suggested by the horticulturist daughter-in-law of one of the modeler.