How to Identify Knotweed
Learn if you are in the right environment., Look at the leaves., Look at the stems., Look at the roots., Double check.
Step-by-Step Guide
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Step 1: Learn if you are in the right environment.
Knotweed grows in moist, partly shaded environments.
They typically are found along roadsides and stream banks or other disturbed areas, but they are not limited to those habitats. -
Step 2: Look at the leaves.
Leaves can be found in a mixture of heart- and spade-like shapes.
They range from 4" – 16" in length.
Leaves found on common knotweed are slender and very small reaching up to 4/5" long. , Stems of a knotweed plant can be reddish-brown and resemble that of a cane.
Common knotweed can be mat like and grow close to the ground reaching up to 8" tall. , They have a rhizome root system that can grow up to 65' long laterally, or there is a taproot system penetrating more than 18" deep. , Sometimes elderberry can be confused for shrubby knotweed due to the stem similarities.
One way to make sure that it is not an elderberry plant is to break off a piece of the stem.
If the inside is hollow it is knotweed.
If it has a whitish grey pith it is probably elderberry.
If it is hollow, proceed to the next step to learn the distinct features of the knotweed species.
Common knotweed can also be confused with spotted spurge.
A way to distinguish the two is by looking for white sticky sap escaping from a broken stem.
If you see this sap you've encountered a spotted spurge plant.
Elderberry also is shorter than knotweed plants. -
Step 3: Look at the stems.
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Step 4: Look at the roots.
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Step 5: Double check.
Detailed Guide
Knotweed grows in moist, partly shaded environments.
They typically are found along roadsides and stream banks or other disturbed areas, but they are not limited to those habitats.
Leaves can be found in a mixture of heart- and spade-like shapes.
They range from 4" – 16" in length.
Leaves found on common knotweed are slender and very small reaching up to 4/5" long. , Stems of a knotweed plant can be reddish-brown and resemble that of a cane.
Common knotweed can be mat like and grow close to the ground reaching up to 8" tall. , They have a rhizome root system that can grow up to 65' long laterally, or there is a taproot system penetrating more than 18" deep. , Sometimes elderberry can be confused for shrubby knotweed due to the stem similarities.
One way to make sure that it is not an elderberry plant is to break off a piece of the stem.
If the inside is hollow it is knotweed.
If it has a whitish grey pith it is probably elderberry.
If it is hollow, proceed to the next step to learn the distinct features of the knotweed species.
Common knotweed can also be confused with spotted spurge.
A way to distinguish the two is by looking for white sticky sap escaping from a broken stem.
If you see this sap you've encountered a spotted spurge plant.
Elderberry also is shorter than knotweed plants.
About the Author
Angela Cooper
A seasoned expert in lifestyle and practical guides, Angela Cooper combines 11 years of experience with a passion for teaching. Angela's guides are known for their clarity and practical value.
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