Noxious
or toxic is the key
& bee-yoo-te-full flower
o n nutters
total nyo nutz
Gelebt haben. Zu sterben, um wieder zu leben.

Yes, it was lantana which was growing in the bushland opposite the houses.
Lantana's not just a weed, it's a declared "noxious weed" - you aren't allowed to plant it, and if you've got it, you are meant to kill it. The plant grows up and over and around and it will take over from the natural bush. (It's a menace.)
Because of the intertwining growth habit of the plant, I think the name of the movie was also chosen to reflect the intertwining relationships of the characters.

Thanks for your response

I believe it's a type of weed that grows in Sydney.It may be the plant in front of Nik's home.
Roger Ebert mentioned it in his review of Lantana in 2002:
"Lantana is, we learn, the name of a tropical shrub that, transplanted to Sydney, prospered and became a nuisance. What is its connection to the film? Perhaps suspicion can also grow out of control, when people get out of the habit of assuming that others are good and mean well."
And it is also mentioned at australianscreen.com.au:
The name of the film confused audiences overseas and some at home. Lantana is in fact a weed a thick bush, hard to get rid of, but with a beautiful flower. Once you go past that, said Lawrence, its all thorns.
Reminds me a bit of American Beauty, with the roses. Seems like a similar thing.

Is that the plant in front of Nik's home, where he threw the shoe in?

Lantana is a plant. It covers large areas and is prickly. You'd get scratched trying to walk through it.