Invasive SpeciesGiant knotweed

Fallopia sachalinensis
FOUND by Joel_Higgins
Limestone, Maine
ID Confirmed
Quality checked by Joel
Peer reviewed by Joel
Field Notes
We went to a previous site of what was identified as Giant Knotweed, located at the edge of a field in Limestone, Maine, to check on its condition and spread. The patch size of this plant species was 60 meters long and 22 meters wide. This patch was located on the boundary edge between two fields. A biodiversity count inside the patch showed 5 different species, while a biodiversity count outside the patch showed 12 different species. The ground inside the patch was really swampy with lots of dead matter. The patch was really a canopy of leaves with very few branches on each stem below the canopy.
A sketch of our study site.
Supporting Evidence
Photo of my evidence.
This leaf measured 41 cm long and 25.5 cm wide. It is elongated and heart-shaped with smooth edges. It did have raised veins on the underside, but without a magnifier, it was difficult to see any short, thin, light-colored hairs growing from the raised veins. Because this leaf is so large, elongated, and heart-shaped, it is not an example of Japanese Knotweed, but does show characteristics of a Giant Knotweed leaf.
Photo of my evidence.
This photo, while not the best, does show a zig-sag stem with alternating leaves.
Photo of my evidence.
This photo shows shows very tall plants with very few branches. It looks like a cave inside with a canopy overhead.
Species Observation: Species Looked For
Did you find it?: 
I think I found it
Scientific name:
Fallopia sachalinensis
Common name:
Giant knotweed
Count of individuals: 
Vegetative structures (plants)
Sampling method: 
Just looking around
Photo of our sampling method.
Place Studied
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Map this species
N 46.912730 °
W -67.852680 °
Observation Site Information
A photo of our study site.
Upland - Field
Trip Information
Edge of a Field
Trip date: 
Wed, 2014-08-06 11:00
Town or city: 
Limestone, Maine
Type of investigation: 
Species and Habitat Survey
Habitat Observations
Species diversity: 
5 different species
Evidence of vectors: 
Recent disturbance
Animals and Wind
Tree canopy cover: 
Open to 1/4 covered
Soil moisture: 


Thank you for this information. I particularly appreciated the information describing how this species differs from Japanese Knotweed. Does anyone have a sense of how widely spread Giant Knotweed is in Maine?


Have you used the Vital Signs mapping tool to look to see where people have looked for F. sachalinensis and either found or not found it? Go to, open up the search tool and look for F. sachalinensis. I'd open up the time window, too. That's where I'd start.

You could also do the same query on EDDMapS ( - they pull Vital Signs data into their database.


Thanks for following up of the site. That giant knotweed is a very impressive plant. Looks like you did some outstanding work looking over the site and collecting data. With your work, it will be much easier to not changes she visiting the site again. Great work!

Your beautiful and annotated illustration has left me near speechless... wow! Thank you for sharing that.

I'm going to go out on a limb (of something sturdier than F. sachalinensis!) and guess that you are on a learning expedition like Dorothy Foote who posted an observation yesterday. Not sure if you talked, but I do note that your evidence statement, especially the first one, is rich with useful details - good work! And very helpful to your viewers.

I compliment you, too, on looking for the hairs on the undersides of leaves. You should be able to see these without magnification (as long as your eyesight is decent), especially on the undersides of YOUNG leaves. They sometimes get knocked off or maybe fall off the older ones. In any case, the size of the leaves you documented is very strong evidence that what you saw was indeed F. sachalinensis.

So, being an artist, do you have any ideas of what you could do with leaves that large? Seems they ought to be useful for something... Or fun for something!

Thanks for sharing your observation, your reasoning, and your beautiful artwork!


My teammate, "MossBoss" AKA Caroline, was the "arisit extradinaire," who created this sketch on her IPAD, using "Paper."

Nice work, Caroline, and great use of your tool at hand!