Many plants can become garden thugs, given the chance
You've watered them, fed them and coddled them. And now they're taking over-sending out tendrils, dropping their seed everywhere and generally bullying their adopted siblings into submission wherever and whenever they can get away with it.
Given the opportunity and the right conditions, some plants can become garden thugs, greedily appropriating more than their rightful share of light, air and space.
Like most responsible guardians, you'll probably wonder how one of your charges grew to be so aggressive. Did you unwittingly purchase an invasive plant from a garden centre? Or, perhaps someone gave you a problem child (people rarely give away slowly reproducing plants, but they're happy to share those that multiply freely). Sometimes the potential bullies even come with a veiled warning.
Years ago my father was digging out a patch of overgrown tawny daylilies (Hemerocallis fulva). I asked if I could have some. “You can have them,” he said, “but you'll be sorry.” He was right. Even a decade later my daylily patch requires constant thinning so that it doesn't completely overwhelm the adjacent poppies and peonies in the border.
And while most garden thugs are attractive, making them hard to resist, I now realize that descriptions such as “soil should be of poor or average fertility,” “drought-resistant,” “makes a great groundcover” or “is a low-maintenance plant” are actually tip-offs that they are potentially invasive. All of these “warnings” refer to several plants in my garden that would happily take over the whole place (or fight each other to the finish) if I let them, including my beloved columbines (Aquilegia spp.).