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===Pharmacology===
===Pharmacology===
The cause of the intense pain has been the subject of scientific research since European explorers first encountered the plant in the mid 19th-century.{{R|AJEBMS}} While the existence of a cocktail of toxins contained within the trichomes is not disputed, the exact nature of it is not yet fully understood,{{R|CONV|FPSB|AGEO2}} although it is known that the active constituents are very stable, since dead leaves found on the forest floor and even decades-old laboratory specimens can still inflict the sting.{{R|ECOS|CONV|ECOBOT}}
The cause of the intense pain has been the subject of scientific research since European explorers first encountered the plant in the mid 19th-century.{{R|AJEBMS}} While the existence of a cocktail of toxins contained within the trichomes is not disputed, the exact nature of it is not yet fully understood,{{R|CONV|FPSB|AGEO2}}. It is known that the active constituents are very stable, since dead leaves found on the forest floor and even decades-old laboratory specimens can still inflict the sting.{{R|ECOS|CONV|ECOBOT}}


Early studies suggested a variety of suspected compounds, such as [[histamine]], [[acetylcholine]], [[5-hydroxytryptamine]] and [[formic acid]], however none of these have been proven to produce a similar intensity or longevity of pain as exhibited by the sting from the plant.{{R|AJEBMS|AAAS|FPSB|AGEO2}} Around 1970 a new compound was identified and given the name [[moroidin]]. It was for a time claimed to be the causative agent, however other research showed that it did not elicit the same response as a sting from the plant.{{R|WAEM|AAAS|CONV2}}
Early studies suggested a variety of suspected compounds, such as [[histamine]], [[acetylcholine]], [[5-hydroxytryptamine]] and [[formic acid]], however, none of these have been proven to produce a similar intensity or longevity of pain as exhibited by the sting from the plant.{{R|AJEBMS|AAAS|FPSB|AGEO2}} Around 1970 a new compound was identified and given the name [[moroidin]]. It was for a time claimed to be the causative agent, however other research showed that it did not elicit the same response as a sting from the plant.{{R|WAEM|AAAS|CONV2}}


In 2020 a previously unknown family of disulfide-rich peptides was identified by a group of researchers and was given the name [[gympietides]].{{R|AAAS|AGEO3|CONV2}} These compounds were shown to produce significant pain responses in laboratory tests. Moreover, their complex structure resembling the [[inhibitor cystine knot]] made them highly stable, explaining how the sting lasts for such a long time.{{R|AAAS|AGEO3|CONV2}}
In 2020 a previously unknown family of disulfide-rich peptides was identified by a group of researchers and was given the name [[gympietides]].{{R|AAAS|AGEO3|CONV2}} These compounds were shown to produce significant pain responses in laboratory tests. Moreover, their complex structure resembling the [[inhibitor cystine knot]] made them highly stable, explaining how the sting lasts for such a long time.{{R|AAAS|AGEO3|CONV2}}

Revision as of 10:26, 30 June 2021

Gympie-gympie
Young plant
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Urticaceae
Genus: Dendrocnide
Species:
D. moroides
Binomial name
Dendrocnide moroides
Synonyms[2]
  • Laportea moroides Wedd.
  • Urtica moroides A.Cunn. ex Wedd.
  • Urticastrum moroides (Wedd.) Kuntze

Dendrocnide moroides, commonly known in Australia as the gympie-gympie, gympie stinger, stinging bush (or tree), mulberry-leaved stinger, or simply stinger, is a plant in the nettle family Urticaceae found in rainforest areas of Malesia and Australia.[3] It is notorious for its extremely painful and long-lasting sting. The common name gympie-gympie comes from the language of the indigenous Gubbi Gubbi people of south eastern Queensland.

Description

D. moroides is a straggly perennial understory shrub, usually flowering and fruiting when less than 3 m (9.8 ft) tall, but it may reach up to 10 m (33 ft) in height. It is superficially similar to Dendrocnide cordifolia, with the most obvious difference being the point of attachment of the petiole to the leaf blade — where D. moroides is peltate, i.e. the stalk attaches to the underside of the leaf and not at the edge, D. cordifolia is cordate. The stem, branches, petioles, leaves, and fruits are all covered in stinging hairs.[3][4]

It has large, heart-shaped, simple leaves about 12–22 cm (5–9 in) long and 11–18 cm (4–7 in) wide with toothed margins, a pointed tip and a cordate to obtuse base shape. There are 6-8 pairs of lateral veins either side of the midrib. The petiole is quite long, about as long as the leaf blade itself, with stipules around 1–2 cm (0.39–0.79 in) long.[3][5]

Fruit

The inflorescence is monoecious (rarely dioecious),[6] and is borne in the leaf axils. It is up to 15 cm (6 in) long, often paired.[5] It carries both male and female flowers which are quite small, the perianth measuring less than 1 cm (0.4 in) across. Flowering occurs throughout the year, but mostly in summer.[3][5]

Fruits of this species are an achene (a tiny seed-like fruit), produced in number in a globular structure which is pink to light-purple in colour and has an appearance similar to a mulberry. Each achene, measuring just 2 mm (0.079 in) long, is contained in a small fleshy sac which derives from the swollen pedicel.[3][5] As with the rest of this plant, the infructescences are also covered in stinging hairs, but are edible if the hairs are removed.[7][8][9][10]

Taxonomy

The type specimen for this species was collected in 1819 by Allan Cunningham near the Endeavour River,[3] and was first described in 1857 by Hugh Algernon Weddell as Laportea moroides in his work Monographie de la Famille des Urticées, published in the journal Archives du Muséum d'Histoire Naturelle.[11] The current binomial combination was published by Wee-Lek Chew in The Gardens' Bulletin Singapore in 1966.[12][13]

Etymology

The genus name Dendrocnide is derived from the Ancient Greek δένδρον (déndron), meaning "tree", and Κνίδος (knídē), meaning "stinging needle". The species epithet moroides is created from the genus name for mulberries Morus, combined with the Latin suffix -oides, meaning "resembling", referring to the mulberry-like infructescence.[5][14] The binomial name may be translated as "mulberry-like stinging tree".[15]

Distribution and habitat

Small plant at Crystal Cascades near Cairns, Queensland June 2021

The species occurs in and near rainforest, from Cape York Peninsula south to northern New South Wales in Australia and also occurs in the Moluccas and Indonesia.[3][5] It is an early coloniser in rainforest gaps, such as alongside water courses and roads, around tree falls, and in man-made clearings.[16][17] The seeds germinate in full sunlight after soil disturbance. Although common in Queensland, it is rare in the southernmost part of its range and is listed as an endangered species in New South Wales.[18][19]

Ecology

Dendrocnide moroides serves as the host plant for larvae of the white nymph butterfly.[3][5] A variety of insects feed on the leaves, among them the nocturnal beetle Prasyptera mastersi and the moth Prorodes mimica, as well as the herbivorous Red-legged pademelons.[17] Fruits are eaten by various birds who distribute the seeds in their droppings.[17]

Toxicity

D. moroides is notorious for its extremely painful sting which may leave victims suffering for weeks or even months. It is reputed to be the most venomous plant in Australia, if not the world.[10][16][17] After contact with the plant the victim will feel an immediate severe burning and stinging at the site of contact, which then intensifies further over the next 20 to 30 minutes and will last from hours to several days before subsiding.[3][17][20] During this time they may get little sleep due to the intensity of the pain.[3] In severe cases it may cause urticaria, and the lymph glands under the arms may swell and become painful,[3][17][20] and there have been rare cases of hospitalisation.[15][16][17][21]

Mechanism

Trichome of the stinging nettle Urtica dioica, similar in basic design to those of D. moroides

Very fine, brittle hairs (called trichomes) cover the entire plant and even the slightest touch will result in them becoming embedded in the skin. Electron micrograph images[20][22] show that they are similar to a hypodermic needle in being very sharply pointed and hollow.[23][24] Additionally, it has been shown that there is a structurally weak point near the tip of the hair, which acts as a pre-set fracture line.[9][24][25] When it enters the skin the hair fractures at this point, allowing the contents of the trichome to be injected into the victim's tissues.[17][20][24][26]

The trichomes will stay in the skin for up to a year and continue to release the toxin cocktail into the body during triggering events such as touching the affected area, contact with water, or temperature changes.[9][17][23] Ernie Rider, a senior conservation officer with the Queensland Parks and Wildlife Service,[16] was slapped in the face and torso with the foliage in 1963, and 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.[16]

Physical contact with Dendrocnide moroides is not the only way that it can cause harm to a person—the trichomes are constantly being shed from the plant and may be suspended in the air within its vicinity. They can then be inhaled, which may lead to respiratory complications if a person spends time in close proximity to the plant.[10][20] The Australian entomologist and ecologist Marina Hurley wrote her doctorate studying two Dendrocnide species of the Atherton Tablelands, west of Cairns, namely D.moroides and D.cordifolia,[20] and was exposed to the airborne hairs over a long period of time. She suffered sneezing fits, watery eyes and nose, and eventually developed an allergy that required medical attention.[16][17] W.V. MacFarlane, who was a Professorial Fellow in Physiology at the John Curtin School of Medical Research at the Australian National University, observed the effects of inhaling the trichomes, and he reported:

The plucking of hairs from the leaves invariably produces sneezing in the operator within 10 or 15 minutes. During early attempts to separate stinging hairs from dried leaves, dust and presumably some hairs were inhaled. Initially they produced sneezing, but within three hours there was diffuse nasopharyngeal pain, and after 26 hours a sensation of an acute sore throat like tonsillitis was experienced.[26]

Pharmacology

The cause of the intense pain has been the subject of scientific research since European explorers first encountered the plant in the mid 19th-century.[9] While the existence of a cocktail of toxins contained within the trichomes is not disputed, the exact nature of it is not yet fully understood,[20][25][27]. It is known that the active constituents are very stable, since dead leaves found on the forest floor and even decades-old laboratory specimens can still inflict the sting.[17][20][26]

Early studies suggested a variety of suspected compounds, such as histamine, acetylcholine, 5-hydroxytryptamine and formic acid, however, none of these have been proven to produce a similar intensity or longevity of pain as exhibited by the sting from the plant.[9][15][25][27] Around 1970 a new compound was identified and given the name moroidin. It was for a time claimed to be the causative agent, however other research showed that it did not elicit the same response as a sting from the plant.[10][15][23]

In 2020 a previously unknown family of disulfide-rich peptides was identified by a group of researchers and was given the name gympietides.[15][22][23] These compounds were shown to produce significant pain responses in laboratory tests. Moreover, their complex structure resembling the inhibitor cystine knot made them highly stable, explaining how the sting lasts for such a long time.[15][22][23]

There has been anecdotal evidence of some plants having no sting, but still possessing the hairs, suggesting a chemical change to the toxin.[27]

Remedies

A commonly recommended first aid treatment is to use depilatory wax or sticky tape to remove the hairs.[28][29] The Kuku Yalanji people of Mossman Gorge used a similar but traditional method, in this case making a juice from the fruits or roots of the plant and applying it to the affected area, then scraping it off with a mussel shell once it became sticky.[30] It is not always successful however, as the hairs are so tiny that the skin will often close over them, making removal impossible.[10][17]

Various other treatments have been tried over time, with most having little or no result. They include bathing the affected area in hot water, applying papaya ointment, xylocaine or lignocaine cream, and even swabbing with dilute hydrochloric acid. All of these are, at best, temporary cures.

Anecdotal stories

Anecdotes of encounters with Gympie-gympie are numerous, and many can be dismissed as yarns, such as one which involves using the leaves as toilet paper (the user would have been stung when they first picked up the leaf, and never proceeded to use it in the intended manner).[17] Nevertheless, some have been documented, such as horses having to be rested after being stung, or even becoming violent and having to be shot.[9] Only one report of a human fatality attributed to any Dendrocnide species (in this case D. cordata) is confirmed, which occurred in New Guinea in 1922.[17][26]

Gallery

  • Mature shrub around 3 metres tall
    Mature shrub around 3 metres tall
  • Inflorescence
    Inflorescence
  • Foliage
    Foliage
  • Detail showing stinging hairs
    Detail showing stinging hairs
  • Fruits and leaves
    Fruits and leaves

References

Wikispecies has information related to Dendrocnide moroides.
Wikimedia Commons has media related to Dendrocnide moroides.
  1. ^ "Species profile—Dendrocnide moroides". Queensland Department of Environment and Science. Queensland Government. 20 October 2014. Retrieved 11 June 2021.
  2. ^ a b "Dendrocnide moroides". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 11 June 2021.
  3. ^ a b c d e f g h i j k F.A.Zich; B.P.M.Hyland; T.Whiffen; R.A.Kerrigan (2020). "Dendrocnide moroides". Australian Tropical Rainforest Plants Edition 8 (RFK8). Centre for Australian National Biodiversity Research (CANBR), Australian Government. Retrieved 11 June 2021.
  4. ^ F.A.Zich; B.P.M.Hyland; T.Whiffen; R.A.Kerrigan (2020). "Dendrocnide cordifolia". Australian Tropical Rainforest Plants Edition 8 (RFK8). Centre for Australian National Biodiversity Research (CANBR), Australian Government. Retrieved 12 June 2021.
  5. ^ a b c d e f g Chew, W.-L.; Kodela, P.G. "Dendrocnide moroides". Flora of Australia. Australian Biological Resources Study, Department of Agriculture, Water and the Environment: Canberra. Retrieved 12 June 2021.
  6. ^ Jackes, B.R.; Hurley, M. (1997). "A new combination in Dendrocnide (Urticaceae) in north Queensland". Austrobaileya. 5 (1): 121–123. JSTOR 41729927. Retrieved 13 June 2021.
  7. ^ Cooper, Wendy; Cooper, William (1994). Fruits of the Rain Forest - A Guide to Fruits in Australian Tropical Rain Forests. GEO Productions. p. 88. ISBN 0-646-19803-3.
  8. ^ Low, Tim (1998). Wild Food Plants of Australia. Sydney: Angus & Robertson Publishers. p. 79. ISBN 0-207-16930-6. Retrieved 12 June 2021.
  9. ^ a b c d e f Robertson, P.A.; Macfarlane, W.V. (1957). "Pain-Producing Substances From The Stincing Bush Laportea Moroides". Australian Journal of Experimental Biology and Medical Science. 35 (4): 381–393. doi:10.1038/icb.1957.41. PMID 13471452. Retrieved 15 June 2021.
  10. ^ a b c d e Schmitt, C.; Parola, P.; de Haro, L. (1 December 2013). "Painful Sting After Exposure to Dendrocnide sp: Two Case Reports". Wilderness and Environmental Medicine. 24 (4): 471–473. doi:10.1016/j.wem.2013.03.021. PMID 23870765. Retrieved 17 June 2021.
  11. ^ "Archives du Muséum d'Histoire Naturelle 9 (1856-57)". Biodiversity Heritage Library. Retrieved 12 June 2021.
  12. ^ The Gardens' Bulletin Sinapore 21 (1965). Vol. 21. Retrieved 12 June 2021. {{cite book}}: |website= ignored (help)
  13. ^ "Dendrocnide moroides". International Plant Names Index (IPNI) (2021). Royal Botanic Gardens, Kew. Retrieved 12 June 2021.
  14. ^ Cooper, Wendy; Cooper, William T. (June 2004). Fruits of the Australian Tropical Rainforest. Clifton Hill, Victoria, Australia: Nokomis Editions. p. 547. ISBN 9780958174213. Retrieved 12 June 2021.
  15. ^ a b c d e f Gilding EK, Jami S, Deuis JR, et al. (16 September 2020). "Neurotoxic peptides from the venom of the giant Australian stinging tree". Science Advances. 6 (38). American Association for the Advancement of Science: eabb8828. Bibcode:2020SciA....6.8828G. doi:10.1126/sciadv.abb8828. PMC 7494335. PMID 32938666.
  16. ^ a b c d e f Burdon, Amanda (16 June 2009). "Once Stung, never Forgotten". Australian Geographic. Retrieved 13 June 2021.
  17. ^ a b c d e f g h i j k l m n Hurley, Marina. "Selective Stingers" (PDF). ECOS. CSIRO. Retrieved 14 June 2021.
  18. ^ Harden, Gwen J. (2001). "Dendrocnide moroides (Wedd.) Chew – New South Wales Flora Online". PlantNET – The Plant Information Network System. 2.0. Sydney, Australia: The Royal Botanic Gardens and Domain Trust. Archived from the original on 14 October 2017. Retrieved 13 June 2021.
  19. ^ "Gympie Stinger – profile". Threatened Species. New South Wales, Australia: Department of Environment and Heritage. Retrieved 25 September 2020.
  20. ^ a b c d e f g h Hurley, M. "'The worst kind of pain you can imagine' – what it's like to be stung by a stinging tree". The Conversation. The Conversation Australia and New Zealand. Retrieved 14 June 2021.
  21. ^ Maor, D.; Little, M. (2017). "Skin contact with a stinging tree requiring intensive care unit admission". Contact Dermatitis. 77 (5): 335–337. doi:10.1111/cod.12830. PMID 29063683. S2CID 3931756. Retrieved 17 June 2021.
  22. ^ a b c Heathcote, Angela (17 September 2020). "The Gympie-Gympie stinging tree contains the same toxins as that of spiders and scorpions, scientists find". Australian Geographic. Retrieved 14 June 2021.
  23. ^ a b c d e Vetter, I.; Gilding, E.K.; Durek, T. "Australian stinging trees inject scorpion-like venom. The pain lasts for days". The Comversation. Retrieved 14 June 2021.
  24. ^ a b c Mustafa, Adeel; Ensikat, Hans-Jurgen; Weigend, Maximilian (July 2018). "Stinging hair morphology and wall biomineralization across five plant families: Conserved morphology versus divergent cell wall composition". American Journal of Botany. 105 (7): 1109–1122. doi:10.1002/ajb2.1136. PMID 30080249. Retrieved 14 June 2021.
  25. ^ a b c Fu, Han-Yi; Chen, Shiang-Jiuun; Chen, Ruei-Feng; Kuo-Huang, L.; Huang, Rong-Nan (2007). "Why do Nettles Sting ? About Stinging Hairs Looking Simple but Acting Complex" (PDF). Functional Plant Science and Biotechnology. Retrieved 16 June 2021.
  26. ^ a b c d MacFarlane, W.V. (1963). "The Stinging Properties of Laportea". Economic Botany. 17 (4): 303–311. doi:10.1007/BF02860137. JSTOR 4252456. S2CID 546456. Retrieved 14 June 2021.
  27. ^ a b c Hales, Lydia (6 February 2014). "Gympie-Gympie losing its sting?". Australian Geographic. Archived from the original on 2 April 2016. Retrieved 13 June 2021.
  28. ^ "Stinging tree (Dendrocnide excelsa) | Children's Health Queensland". Children’s Health Queensland. Queensland Government. Retrieved 18 June 2021.
  29. ^ "Stinging plants". HealthDirect Australia. Australian Government. 8 July 2020. Retrieved 18 June 2021.
  30. ^ Roberts, John; Fisher, Colin (CJ); Gibson, Roy (1995). A Guide to Traditional Aboriginal Rainforest Plant Use. Mossman, Queensland: Bamanga Bubu Ngadimumku Inc. p. 31. ISBN 0-646-22991-5.

External links

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