"A pretty, invasive plant that flowers in late summer and early fall is spreading throughout Michigan. And it's so prolific and tough, it can grow through sidewalks, driveways and building foundations.
Japanese knotweed, native to East Asia, has become such a pervasive invader in Great Britain that those with it on their property can have trouble getting a mortgage or home insurance. It's not to that point in Michigan — and concerned ecologists want to keep it that way.
The law prohibits bringing the plant into the state or moving it around within Michigan.
The shrub-like plant features a hollow, bamboo-like stem and broad leaves in a zigzag pattern up the shoot. It grows up to 10 feet in height. In Michigan, the plant blooms small, creamy white flowers in August and September. Its root network and rhizomes — a stem that grows horizontally under the ground — can grow up to 65 feet away from the weed, shooting up additional plants along its path.
"When you cut it down and try to kill it this year, you haven't killed it; there's the rest underground and it will be coming up again," said Susan Julian, a land specialist with the North Oakland Headwaters Land Conservancy.
Japanese knotweed grows so fast and thick it can crowd out native plant species and destroy natural animal habitat. A YouTube time-lapse video from a British resident shows the plant overwhelming an area of his property in only a few weeks.
...But Japanese knotweed isn't just prolific. It can literally be a home-wrecker.
"It's very tenacious, very hard to kill," Tangora said. "It's one of the first things to grow up through volcanic rock. It can grow through your foundation, your sidewalks. I've had calls from people who had their driveway done two years ago, they had soil brought in and, boom, Japanese knotweed grew up through their driveway."