[Nydhal]

They are occupying the space left behind by human activity. Chemicals will only create more resistant strains just like it did with Amaranth. The reason these plants are successful is the horrendous landscaping traditions especially in new developments. The use of chemicals only reinforces these plants. Basically what's happening is these strains are put under so much pressure in the urban environment that they becomes "super-weeds" and then invade the rest of the landscape. It might be too late to do anything about it now.

[ehvatum]

I don’t think stinknet requires cleared land. Vegetation in the Arizona desert doesn’t form an unbroken canopy. Water is the limiting factor, and stinknet is apparently more efficient than any native plant at immediately converting water into explosive growth and immensely prodigious seed production.

It may well be that the natural course for stinknet is to dominate all other desert vegetation to such an extent that it forms a monoculture that fails to maintain ground nutrients and creates evolutionary pressure toward symbiosis with native plants. But it could take a hundred thousand years for Arizona stinknet to become a good citizen.

[isaacharper]

It does not require cleared land. It will grow under other bushes and trees and pop up right in the middle

[bpodgursky]

More likely some grazing animal figures out how to digest it first.