As the war against invasive species continues, we are always on the look for new potential threats.  And we have one – the marsh dayflower (Murdannia keisak).

Across the country, states spend hundreds of thousands of dollars battling all sorts of invasive species.  One would ask “why spend so much time and money battling these creatures”? The answer lies in the definition of an invasive species.  To be such you must – (1) be non-native to the area, (2) introduced by humans, and (3) cause an environmental or economic problem.  The reason agencies spend so much time and money is #3.  If it is truly a problem, then something must be done.

Based on the invasive species curve (image below), the most cost-effective way to deal with invasive species is to prevent it from ever reaching your area.  This is easier said than done.  The trick is to alert the community about the plant and how it is transported, then keep a vigilant eye out; again, easier said than done.

The next level is Early Detection Rapid Response (EDRR).  This is done by educating the community about the potential threat and eliminating the species as they are found.  As you can see from the curve, this can only be done if the area infested is low.  You must locate and removal very early in the invasion.

For marsh dayflowers, the nearest location where the plant has been confirmed is in Marianna FL and nearby Gadsden County FL to the east, Ft. Rucker AL to the north, and Lake Pontchartrain LA to the west.  So, we are in a position to “prevent” the plant from arriving, but – as mentioned – this is difficult to do.  The next step is EDRR – be vigilant and remove the plant as quickly as they are found.

Step 1 – Preventing; how is the plant dispersed?

One publication suggested a method of seed dispersal is through the digestive tract of waterfowl, like ducks, and other seed eating wildlife.  The seeds can also be dispersed by water currents.  Tracking and managing seed dispersal by water currents would be easier, but the movement by wildlife is difficult.  Based on this, the introduction to our area by waterfowl and wildlife is possible, but not preventable.

Step 2 – Eradicating the plants as they appear in the area

This can only be done if the community is aware of the plant and how to identify it.  So, let’s discuss this.

Marsh dayflower, also known as marsh dewflower – Murdannia keisak, is a semi-aquatic plant that grows along the banks of streams, creeks, ponds, lakes, freshwater marshes (both tidal and non-tidal influenced), swamp forests, disturbed wetlands, and roadside ditches; wherever the soil is wet.  It is an aggressively growing weed that will form thick mats along the shoreline very quickly.

The stems grow horizontally along the surface branching as they extend across the landscape.  Additional roots can grow from nodes along the stems forming a complex, intertwined mat.  The leaves are long, thin, and lanced-shaped, between 0.75 – 2.75 inches long.  They alternate along the stems and possess stiff hairs.  The flowers extend above the mat either as a single bloom, or in clusters of 2-4 flowers. There are three petals about 0.33 inches across and are pinkish or purple white in color.  The fruits are in oval capsules, and the plant can stand between 8-59 inches above the ground.

The invasive nature of this plant includes growing thick mats along the shoreline displacing native plants, some of which are environmentally sensitive and/or protected.  It can reduce water flow and can also reduce human recreation, but impeding boat movement and even access to the water.

This plant is new to our area and may take a botanist to confirm identification.  If you think you may have seen it, please contact your county extension office.

References

University of Florida IFAS Assessment of Non-native Plants – Murdannia keisak – UF/IFAS Assessment – University of Florida, Institute of Food and Agricultural Sciences.

EDDMapS – marsh dayflower (Murdannia keisak (Hassk.) Hand.-Maz.) – EDDMapS State Distribution – EDDMapS.

Marsh Dewflower (Murdannia keisak) Ecological Risk Screening Summary. U.S. Fish and Wildlife Service. ecological-risk-screening-summary-marsh-dewflower.pdf.

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