Desmarestia viridis is a species of brown algae found worldwide. Its common names include stringy acid kelp, green acid kelp, sea sorrel and Desmarest's green weed. The light brown thallus is delicate with a disc-shaped holdfast. It releases sulfuric acid when damaged, destroying itself and nearby seaweeds in the process. They are found in shallow intertidal areas.
Clade: Chromista (Algae)
Species: Desmarestia viridis