Settlers in Australia brought European plants with them, often to the ruination of local ecology. Scottish immigrants often planted rowan trees at their doorways to protect against evil. Here's a snippet I wrote this morning — Rosie and Matt are visiting a ruined farm.
“It looks dead.”
“It’s a rowan tree. Quickbeam, from northern Europe. Deciduous, of course. It has new buds, see? Old magic, to mark the threshold, or keep evil away.”
“Didn’t work, really, if she was widowed twice.”
Another excellent but annoying insight. Rosie ignores it.