Make no mistake about it: this is a one-joke movie, and it lays that joke right out there for you, in the title. Middle America - which in the movie, is treated like a specific physical location, not a region - is being over-run by the titular lethal flora. No-one on the coasts seems to care much, but a couple of intrepid reporters make for the area, led by intrepid TV anchor Brock MacDonald (Ben McCain, actually a genuine TV weatherman!). Conveniently enough, he has a relative (Butch McCain) that's is the sheriff of the infested area. What follows is 90 minutes of media reports, commercials and documentary-style footage, which depicts the attacks, the reaction to them by those who have to adapt to life under a new threat, and worldwide response (presumably shot by various people on holiday, since the movie was five years in the making).
No-one's going to mistake this for great art, but it embraces the idiocy of its central concept and runs with it, far further than you'd expect, especially considering there is absolutely no sense of escalation. The film starts with a tumbleweed attack; these then continue at irregular intervals throughout, and they're basically identical to the first, with lots of closeups of screaming, branches being shaken, etc. It's so daftly inept as to be amusing, but what works better are the interludes, such as the spoof advert for a charity that, for the cost of just three cups of coffee per day, will ensure no child goes with the machete they desperately need, or the lawyer seeking to represent those who have suffered tumbleweed attacks. These are spot-on, and the McCain brothers would likely have been better off concentrating on this angle, rather than the attempts at dramatic acting, which are considerably less successful. Still, if not quite spinning tumbleweeds into gold, this does at least manage an attractive floral centrepiece...