Geniostoma petiolosum, commonly known as boar tree, is a flowering plant in the Loganiaceae family. The specific epithet refers to the relatively long and narrow petioles.
It is a shrub or small tree, growing to 5 m in height. The lanceolate-elliptic leaves are 5.5âÂÂ14 cm long and 2âÂÂ4.5 cm wide. The inflorescences are clustered, 1âÂÂ2 cm long, bearing 5âÂÂ20 small flowers. The ovoid-globose capsules, 6âÂÂ7 mm long, contain small, black seeds in yellow pulp.
The plant is endemic to Australia's subtropical Lord Howe Island in the Tasman Sea. It is an uncommon inhabitant of sheltered forest throughout the Island, especially at lower elevations.