Under Aotearoa's white mistletoe

Welcome back to our first horticulture blog of 2019! This month we’re focusing on another endemic and rare New Zealand plant that you can see at Auckland Zoo – New Zealand’s white mistletoe or Tupeia antartica.

Originally, Aotearoa had nine species of endemic mistletoe that were naturally found nowhere else on earth! One of these, a variety of red mistletoe Trilepidia adamsii was last sighted in 1954 and sadly, is now thought to be extinct. Of the remaining eight species that call New Zealand home, two are found in beech forest, with the other five are found in lowland forest and scrub land.

Part of the Loranthaceae family, which accounts for the majority of mistletoe species worldwide, our white mistletoe is semi-parasitic which sounds a lot worse than it is! Over millions of years, these plants were able to adapt haustorium – special roots which allow them to attach onto the branches of suitable plants and extract water and nutrients from their ‘host’.

Tupeia antartica is only ‘semi’ parasitic because it produces a portion of its energy through photosynthesis via its bright green leaves. The trees these plants alight on, such as whauwhaupaku (five finger), tarata (lemonwood), maire raunui and tree lucerne and are not damaged or hurt by this process, and host plant and mistletoe can co-habitate together within Aotearoa’s forest.

Known to Māori as kohourangi meaning ‘mist of heaven’ or tāpia this shrub-like plant can grow up to one metre in diameter and will produce tiny white flowers that become pink-hued fruit for our native birds to eat. Pikirangi, another New Zealand mistletoe species, means ‘climbing to the sky’ in Te Reo Māori – both beautiful and poetic names for these precious plant species.

White mistletoe can be found on both of New Zealand’s main islands, though the species is currently classified as at risk and declining. Auckland Zoo’s dedicated horticulture experts, work with our partners to ensure that we are representing the full gamut of Aotearoa’s magical landscape, and this can mean actively helping to conserve native plants that are in need of our help. 

The main threats to our native mistletoe come from browsing possums, fungal disease, as well as the decline of New Zealand’s pollinating and seed-dispersing birdlife such as tui and korimako (bellbird) - fewer birds results in less fruit being eaten, and as a result of this, less seeds are dispersed throughout Aotearoa’s forests.   

But there is hope! Studies have shown that after significant possum trapping has taken place, kohourangi has been found growing in regenerating shrubland where it has not been sited before.

Kohourangi, and other native mistletoe species, can be established by humans – as our horticulture team have achieved at Auckland Zoo, but it is not a full-proof method.  Berries from the plant can be crushed into a goo and spread upon suitable host plants. The establishment of mistletoe from this process sits at around 5%, but in 2017 a team led by University of Canterbury and the Christchurch Botanic Gardens were able to introduce these plants with a success rate of 9% within the gardens themselves.

Auckland Zoo supports New Zealand’s target to be predator free by 2050, not only for our native fauna, but for our flora too! If you have precious native plant species like these on your property, you can help to prevent browsing possums from reaching them by wrapping the tree trunks in aluminium bands. We also recommend the use of Good Nature traps, such as their A12 possum trap that will humanely deal with possums in your garden – protecting our native trees and bird-life from introduced predators.

You can see kohourangi growing at the zoo in the nest of trees by The High Country kea aviary. 

Stay tuned for the next blog in this series and if you have any recommendations on plants we should cover or questions for our horticulture experts, flick us an email!