Tristania is a monotypic genus of flowering plants native to New South Wales, Australia, closely related to Thaleropia. The genus had a number of species, but some have been reclassified as Lophostemon and Tristaniopsis. The sole species currently in the genus is Tristania neriifolia. It is commonly known as the water gum. The genus is named for the French botanist Jules Marie Claude de Tristan (1776âÂÂ1861).
It is a small tree, with dense branching. The leaves are evergreen, opposite, simple, lanceolate, 5âÂÂ9 cm long and 1 cm broad. The flowers are produced in dense clusters of 3âÂÂ15 together; each flower is 1âÂÂ1.5 cm diameter, with five small yellow petals and numerous conspicuous stamens.