Invasive Plant Guide

According to the Virginia Department of Conservation and Recreation Murdannia has no known common name and generally goes by Anielema, its former Latin name.  The USDA PLANTS website calls it wartremoving herb and Invasive.org calls it marsh dayflower.  Maryland Extension calls it marsh dewflower or Asiatic dayflower.  The leaves and stems do resemble Asiatic dayflower (Commelina communis).  I don’t know about it’s wart-removing powers.

Murdannia keisak in a marsh on the Maryland Coastal Plain.

Look for mats of Murdannia keisak in freshwater ponds and marshes and along the edges of streams and canals.   It probably arrived in the US from eatern Asia in the 1920s or 30s as a weed of rice cultivation but it has unfortunately spread to natural areas.  It forms dense mats blocking light to plants below. Plants produce thousands of small seeds eaten by ducks and other waterfowl, and the plants spread vegetatively.

Small stands could be hand-pulled before flowering taking care to remove all fragments of the plant.  Larger stands are usually treated using biodegradable herbicides.

Wallace Kaufman pauses on the battlefield

Wallace Kaufman and Knot-weed stalks

April 24, 2015. Along the west bank of Poole Slough, 4 miles east of the Pacific Ocean and Newport, OR.  Here begins the first battle of the third year against the dense stand of giant knotweed that took over about an acre of land where an old barn and a few apple trees stood 60 years ago. When the first battle began in late summer 2012 the knotweed stood in an almost pure stand, stalks up to 10 feet high and two inches thick, two or three stalks from one root, plants 6 to 12 inches apart. Although I cut before they flower, the roots send out new stalks all summer and again in the spring. The stalks are hollow cylinders closed off at knots every 6 to 12 inches. Dried stalks make good pan pipes and flutes. Fresh young stalks can be peeled and cooked as vegetables.

Since the plants begin storing carbohydrates in the roots in early summer, I’ll cut again then and again in the fall. As the lower growing natives begin to compete, the prospects are that I can begin regular mowing with a blade set high to allow low natives to grow while preventing the knotweeds from replenishing their roots.

Each year the stand has been slower growing, stalks slimmer, and height diminished. Here is a scene from the very first attack 3 years ago.

A government report on invasive species’ impacts on threatened and endangered species finds that the topic has not been well researched in most cases.  As I’ve been looking for reports on invasive plant impacts to threatened and endangered species in Maryland I’m inclined to agree!

Find the full report at: http://www.cabi.org/Uploads/isc/Systematic%20Review.pdf

What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species?  Philip D. Roberts, Hilda Diaz-Soltero, David J. Hemming, Martin J. Parr, Richard H. Shaw, Nicola Wakefield, Holly J. Wright, and Arne B.R. Witt

Utah State University Extension has a nice publication summarizing the forage value of a number of noxious weeds and a summary of toxicity reports of many of the plants at the end.  The report was written by Beth Burritt and Rae Ann Hart and published in May, 2014.  There’s a lot of research that still needs to be done on these plants, but it could be a good first guideline if you are interested in using grazing animals to control invasive plants.