Just as mamaku holds the earth together after landslides, so too can it heal wounds and infections in us, explains Donna Kerridge.

Mamaku (Cyathea Medullaris), also known as kōrau, katātā and pītau, is one of my favourite rongoā. It is the largest of our tree ferns and prefers damp soils and frost free hillsides. At the moment mamaku abounds with energy as she parades her flush of new fronds.

Mamaku is a gentle, soothing, nurturing rākau whose role within the ngahere is to soothe Papatūānuku after she has been ripped apart by land slips.

Ka mate he tētē, ka tupu he tētē. As the fronds of the tree fern drop away, young leaves take their place; after decay comes growth.

As a rongoā, mamaku does the same for us, soothing our skin when it is affected by sunburn, insect bites, blisters, eczema, psoriasis or an outbreak of shingles.

Internally (raw or cooked) it soothes an upset puku, giving relief to those with stomach ulcers or colitis. Its mucilaginous texture also soothes our throat from the irritation of a dry cough. Unlike houhere or harakeke, mamaku has no laxative effect.

Topically mamaku flushes at the same time as we are in need of something to soothe our dry itchy eyes, often associated with airborne pollen and dust.

When cooked and still warm, the inner flesh within the young fern frond (koru) is most effective as a poultice to draw out boils.

I have used mamaku with great success to help heal wounds such as long standing diabetic ulcers or surgical wounds that will not heal. To do this, you will need to harvest a young frond (koru) – but before doing so it is important to acknowledge Tāne’s gift to us. Select a frond before its koru starts to open. Once the frond starts to unfurl it has become quite stringy inside and will not snap easily. If it bends rather than snaps leave it there, as it is past its best for medicine. Contrary to popular belief harvesting a frond does not kill the tree, but be sure to harvest from a different tree every time in order to avoid stressing a single tree.

Brush the fur off your frond in the ngahere and thinly peel the outer skin. Slice the flesh into a small stainless steel pot (not aluminium) and heat gently in a little water until soft and tender. Mash the flesh and allow it to cool to body heat before applying a thick layer directly onto the wound. Wrap firmly with a gauze and bandage and leave for three days. Do not open and let the air at the wound during this time. After three days, check the wound for signs of healing. If so, apply more mamaku and re-bandage for another three days. Continue to repeat this process until the wound is fully healed.

It is extremely important to note that if at any time red lines under the skin are seen to be tracking outwardly from any wound before or after dressing, all dressings should be removed and medical help sought immediately. These lines may be the first signs of septicaemia, a blood infection that can be life threatening.

My favourite rongoā using mamaku is as a nourishing and soothing kai, whether sliced and eaten raw, simmered with a handful of berries to make a jelly, stewed with fruits in desserts, or added to vegetable juices and smoothies, like the one below.

Rongoā Smoothie

• 2 handfuls of bush greens such as kaikākā (chick weed, Stellaria spp.) or kōkihi (NZ spinach, Tetragonia tetragonioides)
• Small handful of fresh karengo (Porphyra columbina), optional
• 2 leaves of kopakopa (Plantgo major)
• Flesh and juice of a peeled lemon
• ½ cup mamaku koru, peeled and thinly sliced
• ½ cup of coconut yoghurt
• A knob of peeled raw ginger

Combine all ingredients in your smoothie blender and process until smooth. To get the most from this rongoā drink straight away, do not store as the goodness deteriorates over time.