Environmental Dermatology

Botanical Briefs: Australian Stinging Tree (Dendrocnide moroides)

Cutis. 2023 November;112(5):250-252 | doi:10.12788/cutis.0885

Dendrocnide moroides (also known as gympie-gympie, mulberrylike stinging tree, or stinger) is arguably the most brutal of stinging plants, even leading to death in dogs, horses, and humans in rare cases. They can be recognized as shrubs with heart-shaped, serrated, dark green leaves that are covered in what appears to be soft downy fur with red to dark purple raspberries growing on long stems. After contact, there is immediate piloerection and local swelling, which may disappear after 1 hour or last as long as 24 hours, but the subjective pain, pruritus, and burning can persist for months. One can only treat conservatively with symptom management, and the most successful method of removing plant hair is hair removal wax strips, which are considered an essential component of a first aid kit where D moroides is found.

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Practice Points

Dendrocnide moroides is arguably the most brutal of stinging plants, even leading to death in dogs, horses, and humans in rare cases.
Clinical observations after contact reveal immediate piloerection and local swelling, which may disappear after 1 hour or last as long as 24 hours, but subjective pain, pruritus, and burning can persist for months.
The most successful method of removing plant hair is hair removal wax strips, which are considered an essential component of a first aid kit where D moroides is found.

References

Ensikat H-J, Wessely H, Engeser M, et al. Distribution, ecology, chemistry and toxicology of plant stinging hairs. Toxins (Basel). 2021;13:141. doi:10.3390/toxins13020141
Schmitt C, Parola P, de Haro L. Painful sting after exposure to Dendrocnide sp: two case reports. Wilderness Environ Med. 2013;24:471-473. doi:10.1016/j.wem.2013.03.021
Hurley M. Selective stingers. ECOS. 2000;105:18-23. Accessed October 13, 2023. https://www.writingclearscience.com.au/wp-content/uploads/2015/06/stingers.pdf
Gilding EK, Jami S, Deuis JR, et al. Neurotoxic peptides from the venom of the giant Australian stinging tree. Sci Adv. 2020;6:eabb8828. doi:10.1126/sciadv.abb8828
Dendrocnide moroides. James Cook University Australia website. Accessed Accessed October 13, 2023. https://www.jcu.edu.au/discover-nature-at-jcu/plants/plants-by-scientific-name2/dendrocnide-moroides
Hurley M. ‘The worst kind of pain you can imagine’—what it’s like to be stung by a stinging tree. The Conversation. September 28, 2018. Accessed October 13, 2023. https://theconversation.com/the-worst-kind-of-pain-you-can-imagine-what-its-like-to-be-stung-by-a-stinging-tree-103220
Urticaceae: plant family. Britannica [Internet]. Accessed October 13, 2023. https://www.britannica.com/plant/Urticaceae
Stinging trees (genus Dendrocnide). iNaturalist.ca [Internet]. Accessed October 13, 2023. https://inaturalist.ca/taxa/129502-Dendrocnide
Hurley M. Growth dynamics and leaf quality of the stinging trees Dendrocnide moroides and Dendrocnide cordifolia (family Urticaceae) in Australian tropical rainforest: implications for herbivores. Aust J Bot. 2000;48:191-201. doi:10.1071/BT98006
How the giant stinging tree of Australia can inflict months of agony. Nature. September 17, 2020. Accessed October 13, 2023. https://www.nature.com/articles/d41586-020-02668-9
Chang Y-T, Shen J-J, Wong W-R, et al. Alternative therapy for autosensitization dermatitis. Chang Gung Med J. 2009;32:668-673.

Clinical Importance

Dendrocnide moroides is arguably the most brutal of stinging plants, even leading to death in dogs, horses, and humans in rare cases.^1-3 Commonly called gympie-gympie (based on its discovery by gold miners near the town of Gympie in Queensland, Australia), D moroides also has been referred to as the mulberrylike stinging tree or stinger.^2,4-6

Family and Nomenclature

The Australian stinging tree belongs to the family Urticaceae (known as the nettle family) within the order Rosales.^1,2,3,5 Urticaceae is derived from the Latin term urere (to burn)—an apt description of the clinical experience of patients with D moroides–induced urticaria.

Urticaceae includes 54 genera, comprising herbs, shrubs, small trees, and vines found predominantly in tropical regions. Dendrocnide comprises approximately 40 species, all commonly known in Australia as stinging trees.^2,7,8

Distribution

Dendrocnide moroides is found in the rainforests of Australia and Southeast Asia.² Because the plant has a strong need for sunlight and wind protection, it typically is found in light-filled gaps within the rainforest, in moist ravines, along the edges of creeks, and on land bordering the rainforest.^3,6

Appearance

Although D moroides is referred to as a tree, it is an understory shrub that typically grows to 3 m, with heart-shaped, serrated, dark green leaves that are 50-cm wide (Figure 1).⁶ The leaves are produced consistently through the year, with variable growth depending on the season.⁹

^{Reprinted with permission from Hurley.<sup>6</sup>}

FIGURE 1. Leaf and fruit of Dendrocnide moroides.

The plant is covered in what appears to be soft downy fur made up of trichomes (or plant hairs).^1,6 The density of the hairs on leaves decreases as they age.^2,9 The fruit, which is actually edible (if one is careful to avoid hairs), appears similar to red to dark purple raspberries growing on long stems.^5,6

Cutaneous Manifestations

Symptoms of contact with the stems and leaves of D moroides range from slight irritation to serious neurologic disorders, including neuropathy. The severity of the reaction depends on the person, how much skin was contacted, and how one came into contact with the plant.^1,5 Upon touch, there is an immediate reaction, with burning, urticaria, and edema. Pain increases, peaking 30 minutes later; then the pain slowly subsides.¹ Tachycardia and throbbing regional lymphadenopathy can occur for 1 to 4 hours.^1,6

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