I guess we’d better start somewhere - so why not start with Ageratina adenophora - commonly known in Australia as Crofton weed.

To be clear, the genteel English definition of “weed” as “a plant growing in the wrong place” does not apply in the Australian native garden. I use “weed” as shorthand for “environmental weed” - introduced/exotic/non-native and potentially invasive and damaging to ecosystems. To be terminated where possible, as the movie quote goes, with extreme prejudice.