Urtica ferox

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Urtica ferox


Urtica: from the Latin verb urere which means "to burn"
ferox: From the Latin ferox 'fierce', usually referring to very spiny plants

Common Name(s)

Ongaonga, tree nettle

Current Threat Status

2012 - Not Threatened

Previous Threat Status

2009 - Not Threatened
2004 - Not Threatened


Urtica ferox G.Forst.



Brief Description

Jagged-leaved, stinging, large shrub to 3 m tall, sometimes forming extensive thickets, bearing pairs of thin sharply toothed pointed leaves on long stems. Young parts covered in white needles that inject a painful toxin. Flowers and fruit tiny, in short spikes at base of leaves.

Flora Category

Vascular - Native


Endemic. Found throughout NZ in North and South Islands reaching Otago as its southern limit.


Common in the fringes of bushland. Mainly found in coastal and lowland forest margins and shrublands.


The shrub stands up to 2 m tall with a base up to 12 cm diameter. Its leaves are pale green, 8-12 x 3-5 cm that are borne on petioles up to 5 cm long.

Similar Taxa

None, although other indigenous Urtica species may be confused with U. ferox when it is a juvenile.


November - March

Main Flower Colour


Other Flower Colour



December - May


Not Threatened

Chromosome No.

2n = 48

Endemic Taxon


Endemic Genus


Endemic Family


Poisonous plant

The tree nettle is one of New Zealand's most poisonous native plants. Standing about two metres tall, its coarsely toothed leaves have numerous white stinging hairs (trichomes), up to 6 mm long, at the tip of each tooth as well as on young stalks and leaf veins. These are hollow cylinders with tapered points, which break after piercing the skin, injecting toxins into the tissues, giving rise to pain and a rash. There have been cases of dogs and horses developing neurological problems, with respiratory distress and convulsions within minutes of exposure, often dying within hours, although some do recover. There are also reports of human poisoning in botanical references or the press. Connor, in his book, 'The Poisonous Plants in New Zealand', mentions a group of trampers who developed loss of coordination for three days after being stung. In another instance, a typist developed tingling numbness in the hand after grasping a nettle bush, preventing her from typing for five days. There are also reports of severe headaches, blurred vision and extreme fatigue. A fatal poisoning was described in 1961, when a young man died of paralysis and respiratory problems several hours after walking through a patch of tree nettles. Click on this link for more information about Poisonous native plants.


This page last updated on 30 Jul 2017

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