OOP is the author of something like seven published novels, one of which has been adapted into a movie and another of which may soon be made into a streaming series. Never feel embarrassed to say what you learned today.
A weed is any plant that grows on disturbed or compacted soil without cultivation. Their growth conditions are created by humans and their spread is caused by humans.
My garden is all weeds. Tons of different plants, but some dominate in certain seasons, growing like 5 feet high. Seems to have avoided anything nasty though, no thistles, nettles or brambles.
My neighbour's garden is a thin layer of plastic astroturf. And they let a dog run about on it. Good luck getting dog diarrhoea out of that.
My definition: aggressive spread and resilience to removal.
Plants that are pretty might get more of a 'pass' than ones which are ugly, poisonous or thorny, but ultimately, even the most beautiful flower becomes a weed when it's suddenly everywhere and you are fighting constantly to get rid of it.
Yes, this was a real educational technicality fuckup, it seemed sus but everyone was like "don't you know it's a weed"? - "No, no I do not. And you don't even have a field to worry abut crop yields, it's just a lawn & now there is a flower in it, wtf."
I know it's economy (or even sociology), but it's too close to biology not to directly explain it properly.
Well, "weed" can be a legal definition. A lot of governments have a noxious weed list that either provides for consequences if you suffer that plant on your property, or just an excuse for the government to come on to your property to kill the weeds for you. For instance, Russian Olive is legally a "kill on sight" invasive plant in my area.
Then we go and define things as "invasive" as if the world hasn't been ever-changing for billions of years. As if we know better and need an environment to remain exactly as we found it, forever. As if nature won't just fucking figure it out.