This is a type of a plant – a climbing vine that tends to cover other objects, including other plants. It’s considered an invasive species, because it’s hard to stop.
However, I’ve heard it mostly as an idiom.
I went looking for this, and found surprisingly little on it. Here is a definition of a kudzu plot:
Any long-form narrative that branches off in many different, meandering directions in a manner that is overly or needlessly complicated, especially when they ultimately fail to be resolved in a meaningful or satisfying way.
Urban Dictionary has some similar examples:
The spread of comment threads from a small number of commenters that are dozens of entries in length and thousands of words long.
[…] Kudzu resistance: A working people’s movement created to protect public services to the state of KY. This movement is like the kudzu, powerful, unwilling to back down or give up and they are everywhere.
[…] kudzu capitalism: A dangerous overgrowth of capitalism and corporate power, to where those with the most money gain a disproportionate amount of influence with politicians and government entities
Here’s an example from a page about the usage of kudzu as a metaphor in Southern literature:
Southern culture is filled with kudzu references. Businesses use kudzu as inspiration for names and slogans (“stay here long enough, and we’ll grow on you too” being the most widely used). Mural artists bring the green vine into their work. The literary potential of kudzu is a no-brainer.
[…] Another popular trope is to liken kudzu’s impressive ability to engulf whole houses, cars and bridges with the hold that the American South can have on certain visitors, given the chance. One cannot truly understand the South until they have stayed for long enough to really “let the place wrap around you.”
Why I Looked It Up
From the book I Got Schooled:
Without […] freedom from some of the work rules that have grown up around the profession of teaching like kudzu…
Added on May 18, 2023
In an article entitled “The True Story of Kudzu, the Vine That Never Truly Ate the South,” a scientist tries to clear up some misconceptions:
Like most Southern children, I accepted, almost as a matter of faith, that kudzu grew a mile a minute and that its spread was unstoppable. I had no reason to doubt declarations that kudzu covered millions of acres, or that its rampant growth could consume a large American city each year. I believed, as many still do, that kudzu had eaten much of the South and would soon sink its teeth into the rest of the nation.
[…] Now that scientists at last are attaching real numbers to the threat of kudzu, it’s becoming clear that most of what people think about kudzu is wrong.
So, while perhaps not scientifically accurate, the idiomatic use of “kudzu” holds.