Fear and Loathing in the Landscape

"Japanese Knotweed: The Invasive Plant That Eats the Value of Your Home"

(Headline from a 2014 article in Newsweek

Japanese Knotweed is one plant on the Massachusetts Invasive Species list that gets universal attention for its insidious ways. It rockets out of the ground in spring with bamboo-like stems surging to six feet, leafing densely and more shrub-like than its 'herbaceous perennial' botanical category would suggest. It's rhizomes gallop through the earth from their food banks in massive root clumps. Control and eradication advice reads like the sober experience of guerrilla fighters emphasizing long-haul commitment and integrated, full-spectrum excavation, starvation and poisoning over several years at least. As many homeowners have found, a campaign to eliminate it from established gardens requires relentless vigilance and records few complete victories.

Japanese Knotweed at Halibut Point

The main knotweed intrusion at Halibut Point is restrained by mowing around its perimeter, which curtails expansion into the lawn. To unprejudiced eyes the established clump offers lush heart-shaped foliage in the summer heat and racemes of fragrant flowers in August. Myriad wanna-be offshoots dot the surrounding turf, regularly decapitated by the mower.

Knotweed at the precipice

A few outposts of knotweed struggle to make a go of it in wooded areas where tree competition suppresses them. Fortunately the plants rarely if ever produce viable seed to disperse. But even the smallest bit of stray root can launch a new colony. At one place along the Back 40 trail some root material was evidently thrown over the edge of a gully and sprouted up to embrace ironically the DANGER sign at the precipice. 


 


Knotweed nectar entrances all kinds of bees, wasps, and flies, to its credit in the natural world but probably not to most human passersby.

 

Japanese knotweed thrives in open, often waste places where it can dominate and exclude plants of lesser stature. Aggressive as it is, it has not made substantial inroads at Halibut Point because of regular mowing of the meadows, because it does not adapt well to woodland tracts, and because the original heath plants are better suited to the thin-soiled moors.

It is other invasive non-native plants like bittersweet, English ivy, winged euonymus, buckthorn and honeysuckle that have established a more prominent presence throughout the Park. All of them thrive in the lightly shaded understory of re-developing woodlands on former pasture and quarry land. They have the potential to suppress herbaceous natives and out-compete less robust indigenous shrubs. As the area moves toward a new naturalized equilibrium it will inevitably incorporate substantial numbers of these at some cost to the bio-diversity of both flora and fauna.

These alterations will not necessarily reduce the amount of wildlife in the Park but they will quite likely reduce its variety in the way that suburban development does. Some species will adapt, others shrink to enclaves or disappear. Halibut Point will continue to offer human sanctuary but its ecological riches will be diminished. Other than natural preservation of the coastal rim, this may be the most realistic future for a small-scale, passively-managed tract returning from highly disturbed use.