Alligator weed:  Kudzu of the Waterways

Alligator weed (Alternanthera philixeroides) is an invasive exotic menace.  It was first introduced to this country about a hundred years ago from South America in ballast water from ships.  Many exotic species have spread this way.

This perennial is generally an emergent or rooted floating plant, but it can invade adjoining uplands throughout the southern portions of the United States.  It has become a common terrestrial weed here.

Plants have hollow stems and can grow to 3 feet tall. Opposite, elliptical leaves are thick but non-succulent and are up to 4 inches long. Plants flower in summer with white, miniature clover-like heads at the leaf bases.

When alligator weed spreads it slows water flow.  This clogs our ditches, displaces native vegetation, restricts oxygen levels of water, increases sedimentation, interferes with irrigation and prevents drainage.  When plants die, decomposition lowers the free oxygen in the water and endangers many types of aquatic life.

Another problem is that by slowing down water movement, it is responsible for an increase in mosquito populations.  Mosquitoes prefer shallow stagnant pools and alligator weed facilitates that.

Several chemicals are labeled to control alligator weed, but applying anything to our water can raise red flags.  Concerns about water contamination can be real, especially immediately after treatment.  Only trained and certified applicators should ever apply pesticides to aquatic areas.

There are other solutions.  An insect called the alligator weed flea beetle, (Agasticles hygrophila), is quite effective at controlling this weed.  More importantly, the insect is quite specific in its appetite for alligator weed.

The alligator weed stem borer and the alligator weed thrips also help stifle this pest.  The thrips (distant cousins to the irritants that inhabit our wheat fields in late spring) are the only critters that effectively control terrestrial alligator weed.

Does it have any uses?  It makes a suitable aquarium plant, and yes, you can eat it.  It is readily available in spring, summer, and fall.  Mineral and protein content are high, though some essential amino acids are limited compared to meat proteins.  Taste is not objectionable, either.  That is provided you didn’t harvest it from some stagnant mud hole.

When eaten raw the taste is improved with salt and some type of dressing.  When cooked it also benefits from a little salt and butter or pork fat.  Many palates prefer some vinegar, but I don’t like it on my cooked greens.

Alligator weed would not be near the top of my list simply because of where it grows and the potential problems that could arise.  As mentioned earlier, it accumulates high levels of minerals.  It also accumulates heavy metals readily if they are present, so contaminated waters could pose major problems.

I look upon alligator weed strictly as a survival food, and not a sought after delicacy like some I’ve profiled.  The downside far exceeds the upside, and we would be fortunate if we could eradicate this foreigner from our landscape.  It’s the nutria of the plant world, but it does taste better than cattail, so I guess that’s a start.

Ted Manzer teaches agriculture at Northeastern High School.

About tedmanzer

I grew up in Old Town Maine and got a B.S. at the University of Maine in Plant Sciences/ minor in Botany. From there I moved to West Virginia and earned a M.S. in Agronomy at WVU. I also met my wife there. She grew up in rural WV as the daughter of tenant farmers who raised cattle and hogs. Their lifestyle at times was one of subsistence and I learned a lot from them. I've always been a foraging buff, but combining my formal botanical knowledge with their practical 'Foxfire-type' background opened up my eyes a little more. I recently retired from teaching high school agriculture after 25 years teaching with my wife. Until recently I wrote a weekly nature/foraging column for the local paper ( I also have written several Christian nature/adventure novels that can be purchased on Amazon in Kindle format. One is a five book family saga I call the 'Forgotten Virtues' series. In the first book, Never Alone (presently out of print), a young boy comes of age after his father dies in a plane crash, and he has to make it alone. The second book, Strange Courage, takes Carl from his High School graduation to his recovery from a nasty divorce. The third book, Second Chances, takes Carl from his ex-wife's death and the custody of his son to his heroic death at age 59. The fourth book, Promises Kept, depicts how his grandchildren react and adjust to his death (this one is not yet published). In the final book, Grandfather's Way, his youngest and most timid granddaughter emerges from the shadow of her overachieving family and accomplishes more in four months than most do in a lifetime. I use many foraging references with a lot of the plants I profile in these articles in those books. I also wrote a romance novel titled Virginia. It is available on Amazon and is a different type of romance from a man's perspective.
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