Homalanthus nutans
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malpighiales
Family: Euphorbiaceae
Genus: Homalanthus
Species:
H. nutans
Binomial name
Homalanthus nutans
Synonyms[2]
  • Carumbium moerenhoutianum Müll.Arg.
  • Carumbium nutans (G.Forst.) Müll.Arg.
  • Carumbium pedicellatum (Benth.) Miq.
  • Croton nutans G.Forst.
  • Homalanthus gracilis H.St.John
  • Homalanthus moerenhoutianus (Müll.Arg.) Benth. & Hook.f. ex Drake
  • Homalanthus pedicellatus Benth.
  • Homalanthus populifolius
  • Seborium nutans (G.Forst.) Raf.
  • Stillingia nutans (G.Forst.) Geiseler

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.[3]

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.[4]

Description

Homalanthus nutans is a small tree or bushy shrub up to 5 m (16 ft) 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, 7 to 12 cm (3 to 5 in) long by 6 to 8 cm (2.4 to 3.1 in) 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 1 cm (0.4 in) long, with two compartments, the seeds being partially enclosed by a fleshy aril.[3]

Distribution and habitat

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.[2] It also grows in northeastern Australia, in Queensland and the coastal strip of New South Wales at altitudes of up to 500 m (1,600 ft).[3] 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.[3] It is a pioneer species, found in woodland and on roadside verges, readily colonising disturbed ground.[5]

Ecology

The fruits of Homalanthus nutans are attractive to birds, including the brown cuckoo-dove, the silvereye, Lewin's honeyeater, bowerbirds and currawongs.[3] 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.[3] Modern research confirms the plant's pharmacological activity, with the anti-HIV drug prostratin having been isolated from the plant.[6]

References

  1. Botanic Gardens Conservation International (BGCI) & IUCN SSC Global Tree Specialist Group (2018). "Homalanthus nutans". IUCN Red List of Threatened Species. 2018: e.T135882796A135882798. doi:10.2305/IUCN.UK.2018-2.RLTS.T135882796A135882798.en. Retrieved 29 October 2021.
  2. 1 2 3 "Homalanthus nutans (G.Forst.) Guill". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 8 October 2021.
  3. 1 2 3 4 5 6 Simpson, Donald. "Homalanthus nutans (G.Forst.) Guill. 1837". Some Magnetic Island Plants. Retrieved 10 October 2021.
  4. Field, M. (2005). "Samoa forest holds secret of future drugs". Pacific Islands Report. Archived from the original on 14 March 2012. Retrieved 1 August 2011.
  5. "Flora profile: Bleeding heart". Land for Wildlife. 26 September 2016. Retrieved 10 October 2021.
  6. Cox, Paul Alan (1993). "Saving the ethnopharmacological heritage of Samoa". Journal of Ethnopharmacology. 38 (2–3): 177–180. doi:10.1016/0378-8741(93)90014-V. PMID 8510467.
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