Casuarina cristata aka Black Oak

Casuarina cristata, known as belah, is an evergreen Australian tree. It belongs to the family Casuarinaceae. Kew places its native range in eastern Australia. Plants For A Future lists New South Wales and southeast Queensland. It grows in dry country, often on heavy soils. Some sites have grey or brown clay with lime nodules. It tends to avoid ridges. Its range spans warm temperate, subtropical, and some tropical areas.

This fast-growing tree has an upright form and keeps its leaves year-round. Garden references give a height of about 39 feet [12 metres]. Useful Tropical Plants gives a broader range of 16–66 feet [5–20 metres]. The trunk may reach 1.6–3.3 feet [0.5–1 metre] across. Roots send up suckers, which can build dense stands. This spread matters when choosing a site in a garden. Plants For A Future describes male and female flowers on one tree. Useful Tropical Plants also records fruiting cones.

Grow belah in full sun, with soil that holds some moisture but drains well. Plants For A Future lists sand, loam, and clay as suitable. It accepts mildly acid, neutral, and mildly alkaline soils. The same source says it prefers dry or moist ground. It also cites Australian reports of growth in very wet soil. Unlike many related trees, it does not fix nitrogen, according to that source. Its upright growth suits shelterbelts and woodland canopy planting.

Cold tolerance reports differ and need care in use. Plants For A Future lists USDA zones 8–11. It cites Australian garden survival down to about −7°C. Useful Tropical Plants warns that −5°C may kill mature trees. It also reports damage to young growth at 0°C. These reports do not give one clear frost limit. Plants For A Future notes that cooler British summers change the outlook. It suggests outdoor trials only in the mildest British areas.

People harvest belah for timber, fuel, and tannin. Its bark supplies tannin, while its hard wood takes a smooth polish. Uses include furniture and fences, though the wood lacks durability. Plants For A Future reports no known food or medicinal uses. Both plant-use sources list no known hazards; this does not establish safety for people or pets. Seeds and half-ripe cuttings offer ways to raise new plants. Plants For A Future advises keeping seedlings under glass through their first winter.