It is always interesting to see what may be "invasive" to different gardeners in different locations. Being in a place that is below or near freezing half the year (or at least it seems that way!), I can't ever imagine having olives being invasive or not liking some olive trees growing about. ;)

Thanks for sharing!

FataMorgana

G'day, fellow Aussie!

There are literally thousands of 'herbs' which are potential weeds. After all, a weed is just a useful plant that is growing where you don't want it!

It never ceased to amaze me, when I was 'commercial', that dandelion was my top seller! Others that sold well were stinging nettle, assorted sorrels, chickweed, lamb's quarter and other chenopodiums.

One of my worst ever weeds (apart from evening primrose!) was Amaranth. It took years to eradicate all the self-seeded volunteers.

St John's Wort is also classified as a noxious weed in many parts of the world.

Others that spring to mind include Bergamot, Burdock, Catnip, all the Clovers, Comfrey, Datura, Feverfew, Goldenrod, Ground Ivy, Horehound, Horseradish, Horsetail, Lady's Bedstraw, Oregano, most if not all of the Mints, Motherwort, Nasturtium, Purple Loosestrife, the Brooms, Purslane, Scullcap, Soapwort, Sweet Annie, Vervain, Liquorice.

(OK, some of those didn't just spring to mind! I did a quick search on my data base! I didn't include all in my list, just the best-known ones.)

In parts of Australia, two more really troublesome weeds are Blackberry and Prickly Pear.

I'd be loathe to describe Parsley as a weed, but I've had it self-seed in all sorts of unwanted places, including between concrete pavers. Same with lettuce allowed to go to seed.

I've always been intrigued by the fact that in many parts of Europe, people nurture their (usually potted) geraniums as they would a premature baby. In my part of the world, geraniums become huge, and the only way to control them is to hack them back on a regular basis.

A friend of mine gave me a Brahmi plant - that was something I could watch growing, and not get bored. It had to go, but I had to be careful disposing of it because once that stuff gets into the waterways, it becomes a real thug.

Thanks Daisy, you added a few I had forgotten. It's very dry here, so most of those are easily controlled... I actually wind up nursing many through the Summer and have given up on others. I never put mint or goldenrod in the ground.
I remember the look of amazement on the face of an American friend when she saw poinsettia trees here, probably the same look I wore when I saw a full sized Ficus Lyrata in Brisbane!
I have a zombie olive tree in my back yard. I have repeatedly cut down, poisoned and dug this monster out.. even got in a backhoe to grind the roots down to three feet or more below the ground... and it rises from the dead each time. I have not let the thing fruit for three years and I am still pulling up olive seedlings. The Olive trees that have taken over large areas of the Adelaide hills contribute hugely to the problem of wildfires in Summer. They are fighting for domination with Hawthorn, Blackberry, Boneseed and Broom.