Petalostigma triloculare, known as the long-leaved bitter bark is a rainforest tree of eastern Australia.

It occurs in the drier rainforests, often on sandy soil derived from granite or sandstone, and is sometimes seen on old sand dunes.

Petalostigma triloculare grows as a small tree up to 15 metres (50 ft) tall with a stem diameter of 25 cm (10 in).

The trunk is somewhat swollen at the base, and the bark is a dark grey with some vertical cracks and fissures.

[2] Green or fawn coloured flowers form from October to January, though occasionally as early as July.

It grows as far north as Shoalwater Bay near the Tropic of Capricorn in central east Queensland.