Japanese knotweed is one of the country’s most pervasive and hated invasive plants. The tender red-freckled shoot may look like an innocuous cross between asparagus and bamboo, but it is so powerful it can push through concrete and asphalt. Urban forager and writer Marie Viljoen called knotweed a “thug” and said that it indiscriminately invades agricultural land and backyards. She exacts her revenge in a visceral and delicious way: Viljoen eats it.