Casuarina glauca, commonly known as swamp oak, is a species of flowering plant that is endemic to eastern Australia. It is also known as swamp buloke, swamp she-oak, marsh sheoak or grey she-oak, and is called guman by the Gadigal people in the Dharug language. It is a dioecious tree that often forms root suckers and has fissured and scaly bark, spreading or drooping branchlets, the leaves reduced to scales in whorls of 12 to 20, the fruit 9–18 mm (0.35–0.71 in) long containing winged seeds (samaras) 3.5–5.0 mm (0.14–0.20 in) long.