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American Water-Willow (Justicia americana (L.) Vahl)

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A wetland plant. Although called a "willow", this species is an herbaceous (not woody) plant, and is not closely related to willows (Salix sp.). Its name may refer to a superficial resemblance between the leaf shapes, and the fact that both this species and willows are found in wetlands.

Range - Expand

Native or Not Present
Native or Expanded

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.


Prefers full to partial sun, and shallow, standing water, either stagnant or slow moving, up to three inches deep.

Found in swamps, and on sand, gravel, and mud bars in streams and rivers, especially where the water slows such as at wide areas and on the inside of curves.

This species represents the most cold-hardy of the Justicia genus in North America; most plants of this genus are tropical. Several other species, both native and introduced, occur in North America but only at the southernmost parts.

Next-closest-related plants include other genera of the Justicieae tribe of the Acanthaceae family, including Anisacanthus (desert honeysuckles), Asystasia, Dicliptera, Graptophyllum, Pseuderanthemum, and others. Most of these plants, similarly, are only found in the southernmost parts of North America.

Of these relatives, Dicliptera brachiata is one with one of the wider distributions, stretching farther north. It is closely related and has sometimes been classified in the Justicia genus.

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