Phragmites australis is one of the known thugs of the invasive plant world. I have personally spent many seasons in the field combating the spread of this species in sensitive habitats and know it to be a fearsome adversary. The introduced strain of this giant reed has out-competed native Phragmites in eastern North America, altered species composition and wetlands hydrology, and created virtual monocultures in the habitats it infests. It has all the hallmarks that make a plant species an effective invader - vegetative propagation as well as by wind dispersed seeds, thrives in disturbed areas, able to leap spatial gaps - and now we learn that it has another arrow in its bristling quiver.
Phragmites uses chemical warfare against its neighbors (GWB, take note).
"Harsh Bais, a plant biologist at the University of Delaware, and his colleagues grew native and invasive forms of Phragmites in aquatic labs, from which they collected substances secreted by the plants. They found both invasive and native Phragmites produced so-called gallic acid, a chemical humans use to tan leather. But the invasive plant released the acid from its roots at much higher concentrations than did natives.
Once exuded into the surrounding environment, the toxin targets a structural protein called tubulin found in the roots of neighboring plants. The protein keeps plant roots intact and helps them grow straight in the soil.
Within 10 minutes of exposure to the toxin in the lab, the tubulin of a marsh plant started to disintegrate. In 20 minutes, the structural material was gone.
'When the roots collapse from the acid, the plant loses its integrity and dies,” Bais said. “It's like having a building with no foundation—it's on its way to self-destruction.'
The study is detailed in the latest issue of the Journal of Chemical Ecology."