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October - Toropapa - Native Plant of the Month

Alseuosmia macrophylla

Toropapa are small bushy endemic plants that most people would walk past without noticing. Even the descriptions of toropapa in guide books and plant websites make the plants sound rather boring, with the only real feature of note being their scented flowers. But we would like to suggest that toropapa is one of the most interesting and unexpected plants that we are graced with in Aotearoa.

This is because toropapa is… a mimic!

Most people think of visual camouflage being an animal-only defence strategy, but our very own toropapa breaks the mould for plants. There are six different species of toropapa in NZ, all of which are endemic and all (to the best of our knowledge) are mimics. Toropapa are apparently extremely tasty to herbivores and can be very heavily browsed. This seems to be the selection pressure that has led to their amazing mimicry. Toropapa most often copy the leaf size, colour and shape of unpalatable plants. For example, toropapa species that grow in mountainous cool environments often mimic horopito, whose spicy leaves put off even the most ravenous goats, deer, possums and pigs. In Auckland, our toropapa usually mimic pigeonwood (Hedycarya arborea), or the large-leaved māhoe (Melicytus macrophyllus), which have tough, leathery leaves.

Toropapa mimicry in action. The plant on the left is toropapa, the plant on the bottom right is a species it is mimicking, the large-leaved māhoe (Melicytus macrophyllus)

To see some amazing examples of toropapa’s mimicry, have a look at this blog from Te Papa, which has some extraordinary photos. As one person has suggested - you could plant a whole garden with these mimics and no-one would know that it was all the same plant! If you are interested in growing toropapa in your own garden it can sometimes be found in specialist native plant nurseries. Toropapa do best in shady sites with rich soil that replicates the forest understory that they grow in in the bush.

Perhaps it is because of this mimicry that toropapa often gets such a limited description in guides. It is notoriously difficult to identify and has very few distinguishing features to look out for. But there is a reason that we have chosen toropapa to be October’s plant pin-up. While it is excellent at copying leaves, toropapa has not yet evolved to copy other plants’ flowers. Toropapa flower in spring - from August through until early December. Their flowers are trumpet shaped and range in colour from cream through to dark red, either in a solid colour or striped in darker and lighter streaks. These flowers are a tell-tale identifying feature and this is what you will need to look for to spot it when you are next on a bush walk. The flowers draw attention to themselves with more than just their colour. Toropapa flowers are beautifully scented and you will often smell a plant before you see it. The genus name for toropapa is Alseuosmia, which means perfume grove, a fitting description of their beautiful scent.

Toropapa flowers can vary in colour and dimensions even between neighbouring plants. They are highly fragrant.

Flower showing distinctive hole from nectar robbing.

Toropapa are pollinated by birds, but unfortunately, like many of our tube-shaped bird-pollinated flowers, the plants often fail to set seed due to too few pollinators in the environment. Historically the bush would have been teeming with korimako/bellbirds, hihi/stitch birds as well as tūī, all of whom would have fed on toropapa flower nectar and pollinated their flowers. Tūī are still around of course, but as tough survivors, they know that danger usually lurks closer to the ground, so they don’t hang about in the lower levels of the bush as much, which is where toropapa is found. These days silver-eyes are often the most common nectar-feeding birds in many areas. These little birds have short beaks, which means that they cannot reach the toropapa flowers’ nectar. Instead, they will often ‘rob’ flowers by breaking a hole into the flower tube and drinking the nectar from this. This method is ingenious, but means that the flowers are not pollinated. If a suitable bird visits their flowers and pollinates them, then toropapa produce small lipstick-red fruit, which are also dispersed by birds. Seeing these brightly coloured, oval fruit on plants can be another good way to distinguish toropapa from the plants they are mimicking.

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