Last month I posted about Oriental Bittersweet and put a short slide show on our Derry Cable message boards regarding the identification and removal of it in our own yards. This month our focus will be on Japanese Knotweed.
It is an interesting invasive species in that not only is it so pervasive in our community, but it is also edible! Yes, edible in early spring, for those who enjoy the tangy/tart/sour flavors of rhubarb. I have not tried it so I cannot attest to the flavor or quality. Though I do know where it is growing in Derry – along our roadsides and in our riparian (land near waterways) zones.
In fact, there is some growing across the street from me and it often blocks my neighbor’s view from her driveway. This is because it grows up to nine feet in thick bunches. Its stems look like bamboo (but it of the Buckwheat plant family) and the leaves are large, broad, with wide bases and pointed tips. Right now, from August to September, it is bearing white to light green flowers.
Its edible, it looks like bamboo, what seems to be the problem? Well, it takes over the natural landscape and offers no ecological benefit to the wildlife as it replaces native species and forms what is called a monoculture (single species/cultivar).
And getting rid of it is difficult. On the roadside it is a hazard so it is frequently cut down. However, Japanese Knotweed propagates via rhizomes (underground stems) so all those cut pieces become new plants the following year. Its root structure can be quite extensive so digging it up (as suggested for Bittersweet) is not an option as any root or stem fragment will produce a new cluster of plants.
What do we suggest? Cut it down into stumps and bag those pieces up in dark, plastic garbage bags. If you cut the plant down often enough, it will give up – as long as you do not. Sometimes, adding a bit of white vinegar to the open cut stump might help do the trick as well.
Here are some pictures to help you identify the plant:
photo by John A. Lynch, courtesy of the New England Wild Flower Society