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American Water Willow

Dianthera americana

Family: Acanthaceae (ah-kanth-AY-see-ee) (Info)
Genus: Dianthera (dy-ANTH-er-uh) (Info)
Species: americana (a-mer-ih-KAY-na) (Info)
Synonym:Justicia americana
Synonym:Justicia mortuifluminis
Synonym:Justicia umbratilis



Ponds and Aquatics

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Very high moisture needs; suitable for bogs and water gardens

Where to Grow:

Unknown - Tell us


24-36 in. (60-90 cm)

36-48 in. (90-120 cm)


18-24 in. (45-60 cm)


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

Sun Exposure:

Sun to Partial Shade


Unknown - Tell us

Bloom Color:


Dark Purple/Black

White/Near White

Bloom Time:

Late Spring/Early Summer

Mid Summer

Late Summer/Early Fall

Mid Fall



Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Seed Collecting:

Unknown - Tell us


This plant has been said to grow in the following regions:

Mobile, Alabama

Phoenix, Arizona

Morrilton, Arkansas

Cherry Valley, Illinois

Dearborn Heights, Michigan

Erie, Michigan

Cole Camp, Missouri

Bucyrus, Ohio

Granville, Ohio

Meadville, Pennsylvania

Columbia, South Carolina

Irmo, South Carolina

show all

Gardeners' Notes:


On Jan 13, 2010, larrylb from meadville,pa,
United States wrote:

Dianthera americana (water willow) is quite ubiquitous along French creek in NW PA... This colony-forming, interminable plant can be seen in the the shallow waters and along the sandy islands from June to October... It is not affected by the rising water, which floods the banks and islands periodically in spring and summer or by the ice that covers the entire creek most of the winter... It's quite contrasting, growing among the Acorus calamus (Sweet flag)... Both 'Peterson's Field guide' and the 'National Audubon Society field guide' list it as Justicia americana...


On Aug 27, 2009, BajaBlue from Rancho Santa Rita, TX (Zone 8a) wrote:

Texas native


On May 20, 2009, Delphine61 from Mobile, AL wrote:

We have this in a container in our pond in Mobile, AL and after several years it's spread itself out among the rocks and is even reaching the "bank." Blooms all through May. Our landscaper seemed amused that we'd paid money at the Ponde Shoppe for a weed, but I love the pretty little flowers.


On May 29, 2008, pyromomma from Columbia, SC (Zone 7b) wrote:

I have not grown this, but it is wild and prolific here in SC.

Here is the conversation that I had with the Clemson herbologist when asked to identify the plant:

" J. americana is also called Dianthera americana, often called 'water-willow'. It is in the family Acanthaceae. This is a nice native plant, always found in shallow water and sandy gravel at the margins of rivers or permanent streams.
I have had some luck growing the Justicia in a container set in a pool, so I think it is worth a try. Water circulation should not be needed. I'm not sure if it is generally sold as a waterplant, but a quick check on the internet should help. I love the flowers- they remind me of small orchids. They do like sun, by the way. They may not flower in shade.... read more


On Jun 28, 2003, Terry from Murfreesboro, TN (Zone 7a) wrote:

Pretty and unusual little spotted flowers on this hardy marginal.