Wanted dead, never alive.
Having taken up root on every continent except Antarctica, cogongrass is considered one of the world’s worst invasive species. Unintentionally introduced to the United States from Japan around 1914 as packing material for Satsuma oranges and later cultivated for erosion control and forage grazing trails, the weed has infested an estimated 1 million acres of land in Alabama, Mississippi and Florida.
Its faults? First of all, cogongrass has minute silica crystals imbedded in its leaves that turn each blade of the grass into, well, a literal blade of grass. “Serrated as the teeth of a saw,” as Amy Stewart describes in Wicked Plants: The Weed that Killed Lincoln’s Mother and Other Botanical Atrocities, cogongrass’ leaves are both unappetizing and unhealthy: Its low nitrogen content and poor digestibility make it unsuitable for regular consumption by animals.
But it is cogongrass’ ability to invade and conquer that truly frustrates landowners and environmentalists alike. A single plant produces more than 3,000 wind-born seeds that can be dispersed up to 300 feet — a particularly concerning fact considering germination rates of up to 95 percent have been observed. The grass’s root rhizomes — more than 60 percent of the plant’s biomass — have hard, sharp points that literally pierce the roots and bulbs of helpless neighbors. Also, there is evidence the plant’s residue contains a poison able to inhibit the germination and growth of nearby biota.
Cogongrass’s favorite weapon, however, is fire. Because it burns 15 to 20 percent hotter than natural wild fires, this pyrotechnic plant fuels the fire that its competitors can’t survive. Its underground rhizome network can withstand the heat and easily resprouts and spreads once the smoke has cleared. “Like a phoenix rising from the ashes, fresh young cogon blades spring from the charred remains of the roots and grow stronger than ever after the cleansing infernos,” Stewart writes.
Recently, control measures, such as tilling, mowing and herbicide application, have been implemented to subdue cogongrass infestations, but the battle against this invasive species continues.
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