A familiar sight, cattails edge ponds and wetlands and fill damp ditches across almost the entire U.S. and most of Canada. When I was a kid visiting my Michigan grandparents, I loved seeing the stalks rising like spears from the fringe of their small lake. Red-winged blackbirds often perched atop them, whistling and scolding. They’ve always held some romance for me, but there’s some cool ecological science behind them, too.
This cattail grows in a low, marshy place near my home in a storm water control area. A small pond with a variety of wildlife is a few hundred feet away from this.
Cattails grow tall on long, jointless stems, with the whole plant up to nine feet tall. The alternating leaves are slender. The distinctive brown club at the top of the stem is actually tightly set, tiny female flowers. Depending on species, the flower structure can be up to 12 inches long.
Their root structure is made up of rhizomes, which can interconnect densely in a colony of plants.
According to voyageurcountry.com,
… the flowers are very prolific, one stalk will produce an estimated 220,000 seeds. Even with this number of seeds, cattails colonize by sending up clones from the creeping rhizomes. It has been recorded that a cattail marsh can travel up to 17 feet in a year with prime conditions through the cloning process. Colonization can happen quickly, as one new seed produces a plant, that new shoot in it’s first year will send out a rhizomes for ten feet in all directions and can produce 100 clones in that first growing season.
Cattails are hardy as well as prolific. This handbook on waterfowl management says seeds remain viable in the seed bank for up to 100 years. Because it reproduces so successfully, it easily can crowd out other native species, reducing biodiversity. Controlling its spread requires active management, cutting and/or burning it out, or poisoning it through its root system.
This colony has been growing within the storm water control area for 3 or 4 years. After another couple of years, it could threaten to crowd out other species.
The good news is that fast propagation may be a bonus rather than a curse. There are TWO big benefits provided by cattail stands. One is water treatment: cattails are being used by communities for waste water treatment, among other remediation. And the other is in development of biofuels.
Natural wetlands with cattails help control flooding, but they offer another important benefit, as well. Purification of waste water has been done in the U.S. at least since 1986. Now approximately 500 communities use plant colonies to treat sewage. They can also be used to treat livestock manure and other industrial wastewater. Cattail plants are able to remove toxins including mercury, nitrates, and pesticides, and they deal effectively with bacterial contaminants.
This interesting article by Dr. Isobel Heathcote provides some detail on how wetland sewage treatment works. She outlines advantages and disadvantages.
Advantages include positive aesthetics, habitat creation, and improved cost-efficiency in treatment. Disadvantages may include limited life expectancy of the created wetland, poor phosphorous removal, susceptibility to climate and disease, and the potential for a toxic-waste wetland remaining at the end of its life. Regardless, treating wastewater this way can be more effective than conventional treatments.
The cattail rhizome, the thick horizontal stems that grow just beneath the soil and help it spread so easily, is very starchy. With starch content between 40-60%, the rhizomes offer a potential source of ethanol that could produce more than 10 times per acre as compared to corn. Technologies for processing are still in development but show great promise.
Best yet, the biofuel and water treatment properties may be able to be combined. Blue Planet Green Living includes the following:
Blume suggests one of those “the-problem-is-the-solution” remedies in Alcohol Can Be a Gas. “’How about using the roads to provide the fuel for the cars that use them?” Water gathers around roadsides, allowing runoff filled with toxins like herbicides, oil and antifreeze to be carried for miles downstream. “If each county were to cultivate a 5-foot wide strip of cattail on each side of only 1000 miles of county-maintained roads, boom mowers could shred and harvest up to three crops of cattail per year, producing in theory up to 61 billion gallons of fuel (40% of the U.S gasoline consumption — without using a single acre of farmland while also thoroughly detoxifying road runoff water. Planting energy crops in the nation’s unused median strips along divided highways would generate additional billions of gallons.”
Natural beauty combined with resilience, habitat for wildlife, biofuel combined with water remediation. What more could we ask of this common plant? Besides all that, cattails are a perfect survival food. All year long parts of the plant can be used. Cobs in spring, pollen in summer, roots in fall and winter, the only inedible part is the leaves. This page from Sacred Earth tells much more about using the cattail as food.
My childhood, romantic notions of cattails aside, there are many benefits to cattails. Still, I love to see them when we walk in our neighborhood. But knowing the rest adds to their attraction.