This article was published in the Titirangi Tatler, August 2010

For the Brave and the Beautiful - New Zealand's Stinging Nettles

Nettles have traditionally got a bad press. They are plants that don't tolerate nonsense and fight back when disturbed. The average New Zealander has probably never encountered one and never will unless they go out of their way to find one. Yet they are spread throughout the country and grow from lowland swamps to high alpine slopes. Preferring rich fertile soil with high nitrogen content, the several exotic species can be found lurking behind milking sheds where the slurry of manure is regularly washed out.

The five native species tend to hang around on the outskirts of bush and, inconveniently, along the side of little-used tracks. With pioneering zeal we have eliminated them whenever they have crossed our paths. Understandably, as they give a fearsome jolt when encountered, no matter how gently. The four smaller species look innocuous and although comparatively mild can still cause an irritating and painful reminder to be more careful next time.

It is the larger-growing Urtica ferox that has justifiably given the genus a deadly reputation, but for most encounters it merely sends a stinging message that it is not to be tangled with. It is a message that repeats itself for up to a week, every time you wash the offending part of your anatomy. The stings are like hypodermic syringes with fragile needle tips that can penetrate skin with the lightest brush and then break off with an injection of a toxin named triffydin. It appears to be a cardiac depressant and attacks the nervous system.

You have to be brave to consider planting nettles in the garden.

But we must.

Without the nettles our most elegant butterflies will surely disappear. The Admiral Butterflies rely on the nettles for the correct balance of food to feed their rapacious caterpillars as they grow to become a beautiful gold-encrusted chrysalis. Admirals have two mainland forms, the red and the yellow Admiral, with a subspecies on the Chatham Islands. They have their preferences as to which nettle to lay their eggs on and so feed their young, but it seems as though the Chatham Island Urtica australis is favoured by all the species. That nettle has the attributes of the biggest leaves to provide the most fodder with perhaps the least potent stinging spines. If you can find a remote corner of the garden that you seldom visit, the butterflies will surely thank you for providing a host plant for their young to feed on.