Invasive SpeciesGiant knotweed

Fallopia sachalinensis
FOUND by 18Erm
ID Confirmed
Quality checked by Ms H
Peer reviewed by JP
Field Notes
Mackworth Island has a big problem with invasive plants. We studied in a transect close to the ocean with 6m plots slightly above the ocean in Casco Bay. Mackworth Island was located above us and the plot was located from high to low tide. We studied in early October. The weather was partly cloudy and temperature in the low 60s. My plot was covered in rockweed and knotted wrack where crabs and periwinkles hide. In total, we found over 2 dozen crabs. The vast majority were European Green Crabs, but Asian Shore Crab was also found. Sadly, no native crabs were found except for a shell of a Jonah crab that seemed to be a few years old. There were, on the other hand, a ton of native periwinkles. But the important smooth periwinkle was nowhere to be found. There was also a lot of common periwinkles which are invasive. We also did a timed search around the uplands of the island. There, we found more invasive plants including Glossy Buckthorn, Morrow’s Honeysuckle, Multiflora Rose, and most severely Asian Bittersweet and Giant Knotweed. What we can do to stop this from rolling out is to have the citizens wake-up, and realize that these invasive species are a huge problem. Then, only then, we can try to destroy the species from our area.
Supporting Evidence
Photo of my evidence.
giant knotweed has almost no branches, while Japanese knotweed has quite a bit.
Photo of my evidence.
The stems for the flowers are generally shorter than the leaves, Japanese knotweed's flower stems are longer than the leaves.
Photo of my evidence.
The leaves are shaped like a spade, but Japanese knotweed would have more oval-shaped leaves.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Fallopia sachalinensis
Common name:
Giant knotweed
Sampling method: 
Just looking around
Time search
Photo of our sampling method.
Place Studied
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Map this species
N 43.689942 °
W -70.226687 °
Observation Site Information
A photo of our study site.
Coastal - Beach or dune
Trip Information
Mackworth Marine Transect Investigation
Trip date: 
Tue, 2018-10-09 07:36
Town or city: 
Type of investigation: 
Species Survey
Time of low tide: 
Wed, 2018-10-03 10:15


When you're trying to make the case between such similar species as giant and Japanese knotweed and size is a key distinguishing feature, it's REALLY helpful to make and report measurements.

For next time, right?