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Moonlighter, Stinger or Gympie Gympie

There are four species of Dendrocnide or Stingers/Stinging Trees in the family Urticaceae in Australia. All of them have large hollow silica-tipped hairs on the leaves and twigs. These hairs contain a virulent poison which can cause extreme pain.

Dendrocnide moroides - Moonlighter, Stinger or Gympie Gympie

This plant is reported to be the most virulent species. In the Mackay area it is often called Moonlighter because it appears luminescent in moonlight. It is a fairly common rainforest plant, most likely to be encountered where there has been disturbance to the forest.

This soft-wooded shrub is frequently seen as a single-stemmed plant, 1-2 metres high. The large, long-stalked, alternate leaves are broadly heart- shaped, to about 30 cm x 22 cm, with finely toothed margins. The stalk is attached inside the margin on the underside of the leaf. Mulberry-like, bright pink to purple, juicy fruits are borne in axillary stalks on female plants.

Dendrocnide excelsa
Dendrocnide excelsa
Leaves of Dendrocnide excelsa, the giant stinging tree (above) are similar to those of D.moroides

All parts of the plant are covered in fine stinging hairs. Neither age nor heat destroys the poison. (There are reports of dried Herbarium specimens in excess of 30 years old still being virulent). Even a mere brush with the plant can cause extreme pain. The pain starts as a tingling sensation and develops into stabbing or radiating pain with it being "referred" to other parts of the body, often opposite the affected area. The poison contained in the hairs also causes local redness, sweating and red swollen spots. The background pain may persist for days. Even after it goes, the affected area may become painful after exposure to cold air, cold water or when rubbed, up to two months or more after the original sting.

Originally, the poison was thought to be formic and acetic acids, but later work suggested it was histamine, Acetyl- choline and 5-Hydroxytryptamine. These chemical are known to be responsible for effects such as the symptoms above, as they are involved in allergic reactions, neural transmission and local reactions, such as the increase in the blood supply and hair erection. Later work suggests that the poison principle only acts like ACTH, histamine and HT, but tests indicate the reactions are not actually due to these chemicals. In fact, identification of the chemicals has not been completed.

Forestry workers, in areas where Stingers are common, are supplied with gloves, respirators and anti-histamine tablets, but the bush walker is not likely to have this sort of equipment to hand. Folk remedies suggest that the juice from the Cunjevoi plant (Alocasia brisbanensis) is useful in first aid treatment to relieve the sting, but experienced sufferers have said this is not so!

The most effective first aid is probably achieved by application of 'Bandaid' or sticking plaster. These should be applied then removed, thus pulling out the hollow poison-containing hairs and so preventing long-term pain. The short-term pain caused by poison entering on first contact is probably best handled with common analgesics like Panadol.

Other methods with some benefit for removing the hairs have included scrubbing or rubbing with sand, but care must be taken not to drive the hairs further in, where they will remain for long periods until they break down or work their way out. Our research has indicated that in-depth knowledge of the poisonous principle is scarce and research into identification of the actual chemicals is necessary before precise chemical pain relief is possible.

For safety's sake - watch out for this plant and keep well clear when bushwalking!!

From a leaflet prepared by the Mackay Branch of the Society for Growing Australian Plants (as published in the Queensland Region's newsletter, September 2000).

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Australian Plants online - 2007
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