Casuarinaceae

Casuarinaceae, commonly called the she‑oak family, is a small family of flowering plants in the order Fagales. It comprises two genera, Casuarina and Allocasuarina, with about 60 species native primarily to Australia and the western Pacific, with some extending into Southeast Asia and Pacific islands. Many species have been introduced elsewhere for windbreaks, shade, and dune stabilization.

Description: Members are evergreen trees or shrubs distinguished by slender, pine‑like branchlets. Leaves are greatly reduced to tiny scale‑like teeth arranged around the branchlets, so photosynthesis is mainly conducted in the green branchlets. Flowers are unisexual; male and female inflorescences may occur on the same plant or on separate plants. The fruit is a woody cone that splits to release numerous small seeds, often with wings for wind dispersal.

Taxonomy and phylogeny: The family is placed in the order Fagales. The two genera differ mainly in leaf and cone morphology, but both share the characteristic reduced leaves and photosynthetic branchlets.

Ecology and uses: Casuarinaceae form nitrogen‑fixing associations with actinobacteria of the genus Frankia in root nodules, allowing growth in poor, sandy soils. They are widely planted for timber, fencing, shelterbelts, and dune stabilization. Some species can become invasive outside their native range.

Distribution and habitat: Native to Australia, New Guinea, and nearby Pacific islands, with a range of habitats from coastal to inland woodlands. They tolerant of poor soils, drought, and salt spray, contributing to their use in disturbed or marginal environments.