MYOPORACEAE

Whilst Mabberley (1987) considers the family to comprise about 220 species in 5 genera, Brummitt (1992) recognises only three of the genera (about 213 species), placing the remaining two in the Scrophulariaceae. The plants are trees and shrubs found from Mauritius to east Asia, Australasia through the Pacific to tropical America. Some species of Myoporum Banks & Sol. ex G.Forst. are occasionally grown elsewhere as ornamentals.

Myoporum laetum G.Forst. in New Zealand and Myoporum sandwicense A.Gray in Hawai‘i provide useful timber (Mabberley 1987), as does Eremophila mitchelli Benth. in South Australia (Usher 1974).

One species, Myoporum laetum G.Forst., is a recognised cause of secondary (hepatogenous) photosensitisation in livestock, and in particular in sheep that have been allowed to graze the plant.

Bontia daphnoides L.

von Reis & Lipp (1982) found an herbarium note stating that the fruit is used as an antidote to the poison of Hippomane mancinella L. (fam. Euphorbiaceae).

Myoporum laetum G.Forst.

Ngaio

According to Usher (1974), the bark is used locally to treat ulcers and toothache and the leaves are used to dress wounds, bruises, and baby eczema.

[Further information available but not yet included in database]

This species is a recognised cause of hepatogenous photosensitisation in livestock that have been allowed to graze the plant (Gardner & Bennetts 1956, Tokarnia et al. 2001). In studies of experimental intoxication of cattle (Raposo et al. 1998) and sheep (Raposo et al. 1998) with plant material collected in Brazil and Uruguay, hepatic damage was confirmed by histology. Differences in toxicity between plants collected from different areas were noticed, as were differences in susceptibility to the toxin(s) in the plant. Specifically, of 16 calves fed the fresh green leaves, only one developed mild photodermatitis and one died. Of 17 sheep fed the same material, four died and all surviving sheep developed photodermatitis of the face, ears, eyes, and lips. Seawright et al. (1978) ascribed the toxicity to ngaione, a furanosesquiterpenoid found in the volatile oil of the plant.

References

• Brummitt RK (1992) Vascular Plant Families and Genera. Kew: Royal Botanic Gardens [WorldCat]
• Gardner CA, Bennetts HW (1956) The Toxic Plants of Western Australia. Perth: West Australian Newspapers [doi] [WorldCat] [url] [url-2]
• Mabberley DJ (1987) The Plant-Book. A portable dictionary of the higher plants. Cambridge: Cambridge University Press
• Raposo JB, Mendez MC, de Andrade GB and Riet-Correa F (1998) Experimental intoxication by Myoporum laetum in cattle. Veterinary and Human Toxicology 40(5): 275-277
• Raposo JB, Mendez MC, Riet-Correa F and de Andrade GB (1998) Experimental intoxication by Myoporum laetum in sheep. Veterinary and Human Toxicology 40(3): 132-135
• Seawright AA, Lee JS, Allen JG, Hrdlicka J (1978) Toxicity of Myoporum spp. and their furanosesquiterpenoid essential oils. In: Keeler R, Van Kampen KR, James LF (Eds) Effects of Poisonous Plants on Livestock. pp. 241-250. New York: Academic Press
• Tokarnia CH, Döbereiner J and Peixoto PV (2002) Poisonous plants affecting livestock in Brazil. Toxicon 40(12): 1635-1660
• Usher G (1974) A Dictionary of Plants used by Man. London: Constable [WorldCat] [url]
• von Reis S, Lipp FJ (1982) New Plant Sources for Drugs and Foods from The New York Botanical Garden Herbarium. Cambridge, MA: Harvard University Press [WorldCat]
• [ + 1 further reference not yet included in database]

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