Look-alikes:  Invasive Knotweeds and Native Pokeweed

Invasive knotweeds (Fallopia spp.) are commonly confused with the native look-alike, pokeweed (Phytolacca americana).  Below are some quick tips for telling these two species apart.
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 The easiest way to tell the two plants apart is by fruits, or lack thereof.
Invasive knotweeds (left):  very rarely, you can find fruits on knotweed. Fruits dry, are three-winged, about 8-9mm, with dark, glossy seeds. Photo:  Jil Swearingen, NPS
Pokeweed (right):  berries cover the plant in dark, glossy clusters in late summer. These berries are poisonous to humans, though birds value them. Photo:  David Eickhoff

While leaves can be variable, most knotweeds have rounder leaves than pokeweed.
​Invasive knotweeds (left):  new leaves start out red, turning green with red veins, before becoming completely green. Heart- or spade-shaped. Can be around 12cm long. Photo:  Sarah Green
Pokeweed (right):  leaves are green on top, lighter underneath. Leaves are usually 20-35 centimeters long and oval, tapering on either end of the leaf. Crushed leaves can have an acrid smell.  Photo:  Gianni Careddu

Living stems can be hard to tell apart (both are hollow), but there are a few clues.
Invasive knotweeds (left):  distinctive purple specks on the stem and obvious nodes where leaves attach, looking somewhat like bamboo.  Mature stems are entirely hollow. Photo:  Ancatdubh43
Pokeweed (right):  pinkish-red stem that starts pale and turns almost magenta. Smooth. Lacks the nodes that knotweed has where leaves branch off. Partially hollow. Photo:  Dalgial

When stems die back in winter (both wither after a frost), they can be easier to tell apart.
Invasive knotweeds (left):  stems will redden, then die as it turns to winter, turning reddish-brown.  Stems will usually stand through the winter, even with heavy snows. Photo:  Liz Padalino
Pokeweed (right):  plants will die back after the first frost, stems bleaching white over time.  Dead stems are "squishy," nearly always falling down under snow or even just over winter.  Photo:  Gardenista

Adult plants can look similar, but have slightly different habits to the practiced eye.
Invasive knotweeds (left):  most conspicuous during flowering (pictured). Spread clonally, making large hedge-like clumps or rows with many stems. Photo:  Minnesota Dept. of Agriculture
Pokeweed (right):  most conspicuous during fruiting (pictured).  Spreads by seed, creating many small clumps with just a few stems each that may be somewhat near each other or very far apart. Photo:  JakeC

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