Monday, February 17, 2014

Pretty plant is pretty bad for environment

It’s interesting how a pretty plant can lose its attractiveness once its true nature is revealed.   That’s what happened with me and cogon grass.

I now realize a tall grass I once considered pretty is actually pretty awful

Cogon grass (Imperata cylindrical) is a non-native perennial listed as one of the Top Ten Worst Weeds in the World in the Global Invasive Species database.

Plants on the Ten Worst Weeds list don’t come by that dubious honor without reason. To do so, they must prove to be incredibly invasive, able to survive in a variety of habitats under a wide range of conditions, be difficult to eradicate and be harmful to native plant and animal communities.

Unfortunately, cogon grass fits the bill.

Native to southeastern Asia, cogon grass now covers approximately 500 million acres in 73 countries. It entered the United States in the early 1900s and quickly spread across several southern states. In Florida, where it covers about 700,000 acres, it is listed as a Category 1 invasive — the worst kind — by the Florida Exotic Pest Plant Council.

I didn’t pay much attention to cogon grass until 2013 when I noticed a few patches growing on our property. Before then, I used to drive by fields of white seedheads blowing in the wind and, while I wasn’t sure what kind of grass I was looking at, I admired its beauty. There were times when I even added a few of the fluffy white tops to dried flower bouquets because I thought the feathery white seedheads were so pretty.

Each seedhead produces abundant seeds to float off in the wind spreading the invasive grass far and wide 

Bad Sherry! Had I realized my innocent bouquet gathering contributed to the rampant dispersal of this nasty perennial, I would never have done it.

Wind currents can carry the white feathery seeds — about 3,000 seeds per plant — several miles, but the main way cogon grass spreads is through a network of underground stems called rhizomes. Although the grass can grow up to five feet tall, more than 60 percent of its growth is below the surface in a dense web of sprawling, dirt-hugging roots. Most rhizomes are within six inches of the surface, but some reach four-feet deep into soils ranging from sand to clay to loam and peat.

Like most invasive plants, cogon grass isn’t fussy about where it grows. While it prefers full sun, it can also take root in shady locations. In Florida, cogon grass poses a threat to the health of many pine forests by reducing tree survival and growth. It razor-sharp blades can cut wildlife when they try to navigate through the dense foliage, and its high content of the element silica makes it an unpalatable food source.

The sharp cogon grass blades can be identified by its off-center mid-line vein

Once you become aware of its appearance, you’ll notice cogon grass in a variety of places. I see it along the Florida Turnpike and in fields bordering quiet country roads as well as along busy thoroughfares.

Large fields of cogon grass can be found along highways, country roads and throughout fields

When I realized cogon grass had invaded our property, I figured we could get rid of it by mowing it down. Unfortunately, it’s not that easy. Rather than ceasing its spread, mowing increases it by spreading seeds and rhizome fragments from one place to another.

To think I used to collect the fluffy white seedheads to add to dried flower bouquets...

Because of its intense rhizome system, pulling out clumps doesn’t work either. It isn’t even possible to eradicate cogon grass by burning because it thrives when other species succumb to the heat and flames. The only effective control seems to be repeated applications of herbicides such as Roundup. Even then, complete eradication might take years and during that time who knows how many new cogon grass colonies the wind will carry onto the land.

The more I learn about cogon grass, the less I like it. I’m not sure what we’re going to do to about the infestation on our property but I do know it has changed my outlook. What I used to think of as ‘pretty,’ I now consider ‘pretty awful.’ Instead of seeing swaths of feathery seedheads as spectacles of beauty, I see the menace they present to the balance of nature. Words alone can’t prevent the spread of this aggressive invasive, but they can’t hurt either. Instead of spreading seeds, help me spread the word.


  1. Here we call it guinea grass. It CAN be pulled pretty well in rainy season weather but as with all invasive plants, the key is to get it before it seeds out, so if you pull an area, then keep an eye on what comes up next and get to it before seeding, you can eventually...move it along a bit.
    Here, it is a huge danger for yearly wildfires and people are encouraged to keep it down as it gets perfectly tinder like in the dry season (and as you say, burning only keeps it down for awhile).

    1. just yesterday i tried to pull up some very small clumps of cogon grass but still found it difficult to yank out of the ground. maybe it has something to do with the different soil in our two areas? i managed to get some but not all of the roots. it is so firmly attached that i think pulling would be impractical for larger infestations.