"<i>Scrub</i>. I have used, and shall use, this word so often that some explanation is due to the English reader. I can give no better definition of it than by saying that it means `shrubbery.'"

1864. J. McDouall Stuart, `Exploration in Australia,' p. 153:

"At four miles arrived on the top, through a very thick scrub of mulga."

1873. A. Trollope, `Australia and New Zealand,' c. v. p. 78:

"Woods which are open and passable—passable at any rate for men on horseback—are called bush. When the undergrowth becomes, thick and matted, so as to be impregnable without an axe, it is scrub."

[Impregnability is not a necessary point of the definition.
There is "light" scrub, and "heavy" or "thick" scrub.]

1883. G. W. Rusden, `History of Australia,' vol. i. p. 67 [Note]:

"Scrub was a colonial term for dense undergrowth, like that of the mallee-scrub."

1885. R. M. Praed, `Australian Life,' p. 7:

"Where . . . a belt of scrub lies green, glossy, and impenetrable as Indian bungle."