"Marsh grasses are the tough guys of the plant world. Left alone, they dominate coastal marshes from Texas to Newfoundland. Burn their stems and leaves, and they come back bushier than ever.
They help slow down hurricanes and filter pollution. As impenetrable to humans as a green wall, they shelter birds, fish and endangered mammals, and act as nurseries for commercial species like shrimp and crabs.
But let oil get into their roots and underground reproductive systems, and they can wither and die. If the grasses go, they could take parts of Louisiana's fragile wetlands with them, which means thousands of acres (hectares) of productive and protective marsh could turn into open water.
BP's Deepwater Horizon spill in the Gulf of Mexico has the potential for this kind of damage, and enough oil has coated some patches of marsh grasses to make them appear black when viewed from above.
Fortunately, their green shoots tell another story. Irv Mendelssohn, a wetland ecology expert who has been watching oil's impact on plants for three decades, offers a cautiously optimistic prognosis for their recovery from this latest environmental insult."