Invasive Species: Murdannia keisak, Marsh Dewflower
Marsh dewflower (wart-removing-herb) is an annual, emergent plant that invades wetlands in the southeastern and northwestern United States. Plant stems are succulent, form roots at the nodes, and grow prostrate along the ground. Stems are 12-30 in. (30.5-76.2 cm) long. Leaves are alternate, lance-shaped, and up to 3 in. (7.6 cm) long. In September to November, small, pink, 3-petaled flowers occur singly or in small clusters at the apex of the stems and in the leaf axils. The fruit is a capsule that each contains several small seeds. Marsh dewflower invades water edges and marshes and often grows immersed. It forms dense mats that outcompete native vegetation. Marsh dewflower is native to eastern Asia and was accidentally introduced into the United States, in South Carolina, around 1935.
What are invasive species and why should we be concerned about them?
Taxonomy: Scientific and Common Names for This Species
Commelinales > Commelinaceae > Murdannia keisak (Hassk.) Hand.-Maz.
Synonym(s): aneilima, Asian spiderwort, wartremoving herb, marsh dayflower
Murdannia keisak – USDA PLANTS Profile
Distribution Maps
Marsh dewflower – The reported distribution of this invasive species across the United States (Source: Invasive Plant Atlas of the United States)
Up-to-the-minute distribution maps and why they are important.
Reporting This Invasive Species
What is the best way and place to report the occurrence of an invasive species?
How to report an invasive species sighting to EDDMapS – Early Detection & Distribution Mapping System
EDDMapS – Report an invasive species to EDDMapS.
Cooperative Extension Offices – Find your local Cooperative Extension office on this map provided by USDA.
How to Identify
This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.
Plant
Marsh dewflower is an annual, emergent plant. Plant stems are succulent, form roots at the nodes, and grow prostrate along the ground. Stems are 12-30 in. (30.5-76.2 cm) long.
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| Nancy Loewenstein, Auburn University, bugwood.org | Linda Lee, University of South Carolina, bugwood.org |
Foliage
Leaves are alternate, lance-shaped, and up to 3 in. (7.6 cm) long.
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| Linda Lee, University of South Carolina, bugwood.org | Linda Lee, University of South Carolina, bugwood.org |
Flower
In September to November, small, pink, 3-petaled flowers occur singly or in small clusters at the apex of the stems and in the leaf axils.
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| Linda Lee, University of South Carolina, bugwood.org | Linda Lee, University of South Carolina, bugwood.org |
Fruit
The fruit is a capsule that each contain several small seeds.
| bugwood.org | bugwood.org |
Native Species That Can Resemble Marsh Dewflower
Commelina diffusa, spreading dayflower – Bugwood.org
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| John D. Byrd, Mississippi State University, bugwood.org | Forest & Kim Starr, Starr Environmental, bugwood.org |
Commelina erecta, whitemouth dayflower – Bugwood.org
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| Karan A. Rawlins, University of Georgia, bugwood.org |
Rebekah D. Wallace, University of Georgia, bugwood.org |
Additional Images for Marsh Dewflower
Marsh dewflower – Images at Invasive.org
Additional Information, Biology, Control and Management Resources
Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state’s land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.
United States Land-Grant University System – Find your land-grant university’s college of agriculture, Cooperative Extension office, or other related partner on this map provided by USDA.
Plant Invaders of Mid-Atlantic Natural Areas – National Park Service and U.S. Fish and Wildlife Service
Invasive Alien Plant Species of Virginia – Virginia DCR and Virginia Native Plant Society
Archived Invaders of the Month – The MARYLAND INVASIVE SPECIES COUNCIL (MISC)
Invasive Species – The University of Georgia Marine Extension service