Kawakawa, the ‘holey’ herb of Aotearoa

Kawakawa – photo by Wendy Fox

“… And the Lord spake, saying, ‘First shalt thou take out the Holy Pin. Then shalt thou count to three, no more, no less. Three shall be the number thou shalt count, and the number of the counting shall be three. …. Once the number three, being the third number, be reached, then lobbest thou thy Holy Hand grenade of Antioch towards thy foe,” (Monty Python and the Holy Grail)

Unlike the holy hand grenade of Antioch, which can only be thrown on the count of three and used to snuff out thy foes, the ‘holey’ herb of Aotearoa, kawakawa (Piper excelsum) can be used after the count of three, and used for a variety of purposes.

Cleora scriptaria, the kawakawa loop moth –
By Steve Kerr – https://inaturalist.nz/observations/966307, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=79931894

Kawakawa is a magnificent and delicious endemic herbaceous shrub that grows in the under-story of the forest canopy. Kawakawa is part of the pepper family, Piperaceae, and is in the same genus as kava. But what makes kawakawa holey and delicious I hear you ask? Well, you are in for a treat!

The kawakawa looper moth (Cleora scriptaria) is an endemic Lepidoptera from the family Geometridae. C. scriptaria is a mottled brown moth with high variation of colours and patterns between individuals. The caterpillars are pale green and have a white and/or dark stripe down each side of their body. This allows them to camouflage against the underside of leaves.

The caterpillars feed on the kawakawa leaves creating holes, despite the plant’s anti-insect compounds. The holes in the middle of the leaves are usually made by small caterpillars, and the holes on the outer edges of the leaves are mostly done by larger caterpillars. It is widely believed that the caterpillars munch on the tastiest leaves, making them the best leaves to harvest for tea or other uses.

Kawakawa looper caterpillar – By Tony Wills – https://www.inaturalist.org/observations/1181569, https://www.inaturalist.org/photos/1492012, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=74214641

I personally love kawakawa tea. It is an excellent pick-me-up first thing in the morning, one dried leaf in a cup of hot water, left to steep for 5-10 minutes, is just bliss. It has a peppery and grassy flavour that is more subtle than other herbs can be. The longer you leave it to steep the stronger it gets, and usually you can get two cups of tea from one leaf, it just needs to steep for twice as long the second time.

Kawakawa has an exciting array of medicinal properties. It is known to have anti-inflammatory and antibacterial properties, and can be used for a variety of ailments. Kawakawa is good for gut and urinary system health. One interesting use for kawakawa is that it can be chewed to relieve tooth ache, with the suggestion that it could be rubbed on a baby’s gum if they are teething. How cool is that?!

Kawakawa is fantastic for treating skin complaints like eczema, psoriasis, cuts, wounds, and even acne. For skin complaints, it is usually used topically by applying a balm, cream, or poultice to the affected area. Kawakawa balm is a great item to have on hand, and there are many different recipes on how to make it. A friend, Gina, gave me the recipe below that she uses and is easy to make.

Kawakawa leaf – photo CC-BY Wendy Fox

Proper tikanga (procedure and practice) should always be followed when working with rongoā (traditional Māori medicine), and karakia (prayer or incantation) should be said before harvesting, and making remedies.

Kawakawa is a truly extraordinary plant. Given that moths try to munch their way through the leaves, Hodge, Keesing & Wratten tested how kawakawa shrubs would respond to different levels and types of leaf damage using kawakawa looper caterpillars and a hole punch. They found that kawakawa was not influenced by the type of damage and it can lose 90% of the area of a leaf and carry on as if nothing had happened.

Unlike many other plants, kawakawa does not produce extra chlorophyll in damaged leaves to compensate for the loss of area, nor do the plants seem to drop the damaged leaves any sooner compared to undamaged leaves. Hodge, Keesing & Wratten found a 10% difference in the mean percentage of leaf retention between leaves with 0%, 1%, 5%, and 90% damage. This may be due to the relatively short leaf retention periods of Kawakawa. However, most plants will drop leaves with higher damage so they can function more efficiently.

Kawakawa – photo CC-BY Wendy Fox

While no one expects the Spanish Inquisition, there have been a string of ongoing studies surrounding kawakawa leaf damage and its anti-insect compounds, including studies looking at its potential use in protecting crops from insect herbivory.

More research is needed to fully understand this incredibly versatile and hardy plant, which is, unsurprisingly, becoming a popular garden plant. So join the caterpillars and enjoy the ‘holey’ herb of Aotearoa too.

This article was prepared by postgraduate student Wendy Fox as part of the ECOL 608 Research Methods in Ecology course.

Hodge, S., Keesing, V. F., & Wratten, S. D. (2000). Leaf damage does not affect leaf loss or chlorophyll content in the New Zealand pepper tree, kawakawa (Macropiper excelsum). New Zealand Journal of Ecology, 24(1), 87–89.

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