BRIGHT STAMENS: Above, flowers at Mahy Reserve, Ohope. A profusion of bright crimson stamen forms the most visible part of the pohutukawa flower. At the base of the stamen can be seen the shallow nectar-bowl. Photos Illmars Gravis 2018

SUMMER has well and truly arrived in the Eastern Bay, and our beautiful sandy beaches are attracting visitors from near and wide.

Our beaches are even more special for their backdrop of large stately pohutukawa trees (Metrosideros excelsa) bursting into a profusion of crimson flowers. This tree holds an important part in our culture, with Maori regarding it as a chiefly tree (rakau rangatira) and the blossom refered to as kahika.

While we may take these beautiful trees somewhat for granted as part of our natural environment, it is, in fact, not as common as it once was in coastal areas of the upper North Island.

Once pohutukawa, and several species of rata, could be found in a continuous coastal strip as far south as Poverty Bay on the east coast, and Northern Taranaki on the west coast.

These populations have been reduced to a few relict stands and isolated individuals, with our Eastern Bay population an important environmental taonga.

Pohutukawa is adapted to coastal conditions, where the largest and healthiest specimens are usually found, with deep and tenacious roots allowing it to colonise rocky outcrops and coastal cliffs.

It is also commonly seen colonising bare ground such as landslips and lava fields where it can use its roots to extract hard-to-reach nutrients and water. The sturdy and massive roots and trunks of these trees are reflected in the name of the genera Metrosideros, meaning “iron-hearted”.

Other species in the genus are rata, and together these species belong to the myrtle family, which includes manuka, kanuka, and eucalyptus species. The species name excelsa, refers to its outstanding, or sublime, appearance when in flower.

The especially hard wood was highly valued for boat building, as its nature made it particularly suitable for curved pieces required for the structural frame of boats. Where older wooden boats have used pohutukawa for the structure, and kauri for planking, the pohutukawa have often been found to be more durable and longer surviving than the kauri.
However, it is undoubtably the spectacular flowers of these trees that now hold such a special place in our hearts, both for their distinctive crimson colour, and the fact that the pohutukawa flowering heralds our summer and a time of festivities and relaxation. It is the smothering of bright crimson flowers reaching their peak in mid-December that have seen the pohutukawa affectionately referred to as the New Zealand Christmas Tree.

Flowers are also highly valued by our native and non-native nectar-feeding birds, attracted by the nectar at the base of the flowers, thereby pollinating the flowers, and ensuring seed becomes fertile. A more modern pollinator taking full advantage of the offerings of the pohutukawa flower is the introduced honey-bee.

Flowers are a type known as “brush blossoms”, formed by a mass of bright red stamen with a shallow bowl of nectar at their base. Masses of flowers displayed at the canopy of the trees attract birds from a distance, and seeking nectar, they pollinate the flowers by transferring pollen from the male stamen to the female stigma.

Fertilised seeds develop in an ovary at the base of the stigma, in time forming a seed capsule that spreads its numerous wind-borne seeds in winter. Tiny wind-borne seeds are ideally suited to gaining a hold in rocky cracks and crevices where enough nutrients have accumulated to nurture the growing seedling.

It is due to the wind-borne nature of these seeds that the trees can often be found colonising rocky off-shore islands, such as Rangitoto in the Hauraki Gulf, and Whakaari-White Island in the Bay of Plenty.

Here in the Eastern Bay, at Ohope Scenic Reserve, one can experience one of the last remaining stands of mature pohutukawa and rewarewa dominated bush, still intact largely thanks to the tireless work of volunteers undertaking pest control.
Possums browse heavily on spring vegetation, as well as mature vegetation, and if left unchecked they can lead to a premature death of trees that should be able to live to a thousand years at least.

The East Cape is also famous for what is reputed to be the largest pohutukawa in the country. Te Araroa is home to a tree known as Te Waha O Rerekohu “The mouth of Rerekohu”. This is certainly the largest pohutukawa in the country and may well be the oldest at over 400 years.

So, as you enjoy the coming summer days against a backdrop of crimson flowers, clear blue skies and glistening white sands, take a moment to appreciate this special taonga we are blessed to have amongst us. If you would like to find out more about the ecology, culture, and history of the Metrosideros species, check your local library for Pohutukawa and Rata. New Zealand’s Iron-Hearted Trees by Philip Simpson.

Finally, I would like to thank the Whakatane Beacon and Eastern Bay Life for supporting this column over the last year, and supporters and followers of my blog Aotearoarocks.blogspot.com. I look forward to more exploration of our unique and dynamic Eastern Bay of Plenty and hope you will join me. Merri Kirihemiti.

For more follow www.aotearoarocks.blogspot.com

Natural history

By Llmars Gravis