Homalanthus nutans, known locally as the mamala tree, is a species of plant in the family Euphorbiaceae. In Australia it is known as the bleeding heart and the Queensland poplar.
Samoan healers use the tree's bark in a concoction made to treat hepatitis. Research has indicated that a chemical from the bark called prostratin has in vitro activity against HIV.
Homalanthus nutans is a small tree or bushy shrub up to 50NaN0 tall. The trunk has fairly smooth, greyish-brown bark. The rather stout branches are green or reddish, and the twigs exude a white, milky sap when damaged. The alternately arranged leaves have a pair of small stipules at the base of the long petiole, which is often a reddish colour. The leaf blade is hairless, heart-shaped or triangular, 7to long by 6to wide, with a smooth, untoothed margin. The underside is often greyish and mature leaves turn red as they age. The inflorescence is a terminal yellowish-green spike, the male and female flowers being separate. The male flowers are small and petal-less, with globose anthers. The few female flowers, near the base of the spike, are also without petals, and have a pair of short styles. The female flowers are followed by capsules about 1cm (00inches) long, with two compartments, the seeds being partially enclosed by a fleshy aril.
Homalanthus nutans is native to various tropical Pacific islands: the Caroline Islands, the Cook Islands, Fiji, New Caledonia, Niue, Samoa, the Society Islands, Tonga, Tubuai Island, Vanuatu and Wallis and Futuna.[1] It also grows in northeastern Australia, in Queensland and the coastal strip of New South Wales at altitudes of up to 500-2NaN-2.[2] The seeds have a long dormancy period, but germinate readily when the conditions are suitable, such as when the previously shady forest floor becomes illuminated by direct sunlight.[2] It is a pioneer species, found in woodland and on roadside verges, readily colonising disturbed ground.[3]
The fruits of Homalanthus nutans are attractive to birds, including the brown cuckoo-dove, the silvereye, Lewin's honeyeater, bowerbirds and currawongs.[2] In Samoa, the plant has a number of uses in traditional medicine. An extract from the bark is used against hepatitis, and freshly crushed leaves are used to control bleeding.[2] Modern research confirms the plant's pharmacological activity, with the anti-HIV drug prostratin having been isolated from the plant.[4]