Casuarina glauca, commonly known as Swamp She-oak or Grey She-oak, is a dioecious tree native to coastal regions and estuarine environments of eastern Australia, from Yeppoon in Queensland to Bermagui in New South Wales. It is often found in saline wetlands and along brackish waterways. This species typically grows to a height of 26-66 feet (8-20 meters) and forms dense stands that can alter local ecosystems. The tree has distinctive fissured, scaly bark and needle-like branchlets that resemble pine needles, with tiny scale-like leaves that contribute to its unique texture. The foliage is a blue-green or grey color, which adds to its common name. Casuarina glauca is notable for its ability to fix nitrogen through root nodules, which enriches the soil and supports the growth of other plants, including orchids like Dendrobium teretifolium.

Swamp She-oak is valued for its ability to stabilize soil and for its use in windbreaks and coastal reclamation projects. It is also used for ornamental purposes in large landscapes due to its distinctive appearance. In cultivation, it requires full sun to part shade, tolerates a range of soil types including poor soils, and can withstand occasional flooding and saline conditions. However, it is important to be aware of its potential invasiveness when grown outside its native range, as it can outcompete local vegetation and alter habitats. Gardeners should check local regulations before planting.CC BY-SA 4.0