Dendrocnide moroides, also known as the stinging brush, mulberry-leaved stinger, gympie gympie, gympie, gympie stinger,[1] stinger, the suicide plant, or moonlighter, is a plant common to rainforest areas in the north-east of Australia.[2][3][4] It is also found in Indonesia. It has stinging hairs which cover the whole plant and delivers a potent neurotoxin when touched, by the small bulb that is found on the tip of the stinging hairs being broken off and penetrating the skin to inject the toxin.[5] It is the most toxic of the Australian species of stinging trees.[2][4] The fruit is edible to humans if the stinging hairs that cover it are removed.[6]

D. moroides usually grows as a single-stemmed plant reaching 1–3 m (3 ft 3 in–9 ft 10 in) in height. It has large, heart-shaped leaves about 12–22 cm (5–9 in) long and 11–18 cm (4–7 in) wide, with finely toothed margins.

Ecology [ edit ]

The species is unique in the genus Dendrocnide in having monoecious inflorescences in which the few male flowers are surrounded by female flowers.[4] The flowers are small, and once pollinated, the stalk swells to form the fruit. Fruits are juicy, mulberry-like, and are bright pink to purple, they also contain dense hair-like structures capable of injecting a toxin. Each fruit contains a single seed on the outside of the fruit.[7]

The species is an early coloniser in rainforest gaps; seeds germinate in full sunlight after soil disturbance. Although relatively common in Queensland, the species is uncommon in its southernmost range, and is listed as an endangered species in New South Wales.[3][8]

The giant stinging tree and the shining-leaved stinging tree are other large trees in the nettle family occurring in Australia.

Toxicity [ edit ]

D. moroides fruit fruit

Contact with the leaves or twigs causes the hollow, silica-tipped hairs to break off, penetrate the skin and inject the toxins.[9] The hairs cause an extremely painful stinging sensation that could last from several hours to 1–2 days, recurring to a lessening degree for several months or more whenever the area is touched, exposed to water, or subjected to temperature change. The injured area becomes covered with small, red spots joining together to form a red, swollen welt. The hairs are also believed to be released to the air when the plant is cut or cleared in large areas. Workers without respiratory protection have reported sneezing, runny noses, mild nasal bleeding and throat irritation while cutting or clearing. Ernie Rider, who was slapped in the face and torso with the foliage in 1963, said:

For two or three days the pain was almost unbearable; I couldn't work or sleep, then it was pretty bad pain for another fortnight or so. The stinging persisted for two years and recurred every time I had a cold shower. ... There's nothing to rival it; it's ten times worse than anything else.[10]

The sting does not stop several small marsupial species, including the red-legged pademelon, insects, including the Prasyptera mastersi,[11] and birds, from eating the leaves.[7]

Moroidin, a bicyclic octapeptide containing an unusual C–N linkage between tryptophan and histidine, was first isolated from the leaves and stalks of Dendrocnide moroides, and subsequently shown to be the principal compound responsible for the long duration of the stings.[12]

Dendrocnide moroides sting Chemical structure of moroidin, the bicyclic octapeptide responsible for the long-lasting pain caused bysting

There has been anecdotal evidence of some plants having no sting, but still possessing the hairs, suggesting a chemical change to the toxin.[13]

See also [ edit ]

References [ edit ]

Further reading [ edit ]