Weed of the Week #8 – Japanese Knotweed (Polygonum cuspidatum: Polygonaceae)

The first time I saw this weed I seriously thought it must’ve come from another planet. I was renovating a garden and all along the backside of the garden was a grove of Japanese knotweed. This weed can grow to over 15 feet in one growing season! It is easily identified in the spring, when nothing else is growing and it is already 1-2 feet tall with red veiny stems and triangular shaped leaves. In the summer it has large clusters of conspicuous white flowers. Just like a lot of other weeds, this one was introduced from Japan in the 1807s as an ornamental plant and sold in nurseries for the next 50 years! The emerging shoots can be picked in the spring and after boiling them they taste a lemony flavor. I haven’t tried it, but if you have let us know.

Where It’s From: temperate East Asia

Where It’s Found: Disturbed areas that are not maintained

Where To Find It: Vacant lots, along highways, drainage ditches, and uncultivated gardens

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