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It is certainly one of the most remarkable vegetable productions I have seen,’’ wrote amateur botanist Richard Taylor in his journal on March 18, 1845.
He was referring to the plant that would carry his name, Dactylanthus taylorii, New Zealand’s only fully parasitic indigenous plant. Part of its charisma is that its future is entwined with that of our rare native short-tailed bat.
The plant is what botanists call dioecious – it has separate male and female flowers, possibly produced on separate plants. This type of reproductive system hints at its ancient ancestry: the oldest dactylanthus pollen samples found date back 23 million years. It is in the family Balanophoraceae, which is represented mostly in tropical areas. Dactylanthus taylorii is the only plant in its genus: it is unique – or as some would argue, weird.
Known among Maori as pua o te reinga (flower of the underworld), wae wae atua and putiputi o te pouri, it became known as the hades (hell) flower, but today it is most commonly called dactylanthus. Wae wae atua means ‘‘fingers of the gods’’, while ‘‘dactylanthus’’ is a Latin term meaning ‘‘finger-flower’’. The flowering inflorescence (a shoot that bears clusters of flowers) is about the size of a thumb, while the female inflorescence looks like a cluster of hairy fingers.
The buds open over three or four days and each produces a copious amount of nectar – about two millilitres – which the plant keeps refreshing. Taylor passed several inflorescences before stopping, and upon closer inspection found that what had seemed like a fungus was actually a plant in full flower, with ‘‘a calyx containing a kind of pollen with rather a disagreeable smell.’’ Others have described the strong smell as sweet, musky, and distinctive. The male and female produce slightly different scents.
Pollinators were basically unknown until a 1994 video revealed that shorttailed bats were drinking the nectar, transferring pollen. Unusually, they spend large amounts of time foraging on the forest floor, using their folded wings like front legs to get about, filling a similar niche in our ecosystem as mice do in the northern hemisphere. Indeed, they are about the same size, so it should probably be no surprise to discover that mice and rats are also dactylanthus pollinators.
Unfortunately, it is not just bats that are attracted to the scent of dactylanthus. A study found that dactylanthus nectar’s scent has DOC is asking everyone to keep their eyes peeled for Dactylanthus taylorii, both for live plants in the bush and for anyone who might be attempting to sell plants or wood roses. Historically there were reports of dactylanthus growing in Coromandel, the bush between Hamilton and Raglan (Whatawhata Hills), Te Kauri Forest Park and Sanatorium Hill/Maungakawa: a rediscovery in these areas would be especially exciting. Please contact your local DOC office if you spot dactylanthus – new finds are nationally significant. cinnamon notes, an odour used by trappers to lure possums. Possums adore dactylanthus, greedily eating the entire flower, meaning no seed is set. They are capable of destroying an entire season’s population in a night.
Photographer David Mudge has taken time-lapse photographs of dactylanthus flowering, providing tantalising insights. The inflorescences almost appear to be breathing as they open and close slightly through the day/night cycle. Bugs, including spiders and flies, enjoy visiting the plants (see http://youtube/ lwOaqvnhW-Q).
Kakapo coprolites (fossilised faeces) have been found to contain large amounts of dactylanthus pollen, suggesting that they, too, were pollinators. Scientists are watching with interest the kakapo released on to Hauturu/Little Barrier Island about two years ago: dactylanthus still survives there.
However, we still don’t know how the seed would naturally be distributed: it is probably via some sort of animal. The plants produce incredibly tiny stonefruit – there are about 3500 fruit in a handful. Unfortunately, mice find them delicious, crunching up the seeds. Rats also eat the fruit, but pass the seeds intact, so probably act as dispersers.
Dactylanthus seed can remain viable for at least seven years in the soil. Plants have been successfully propagated from seed at Waikato University and Pureora Forest Park, where it is being studied. Dactylanthus prefers moist shade and takes between four to nine years to flower.
Being a root parasite, the plant is usually unseen, visible only when it
A young Dactylanthus taylorii tuber (partly excavated), with a developing bud. flowers, which makes it very hard to find. Sometimes the top of its tuber is visible through the leaf litter, looking a bit like a warty wood burr. The ‘‘warts’’ produce the flowers and there may be hundreds of these on the tuber.
The tuber is quite hard and may grow up to the size of a small child’s head, although sometimes several will aggregate together. The largest clump found to date measured around 50 centimetres across.
Not only does dactylanthus lack leaves, it lacks chlorophyll, and has no way of taking up water by itself, relying on its host to do these tasks. The plant and host are known to communicate, probably hormonally. The tuber sits over the root of the host plant, meeting but not merging with it (unlike mistletoe), causing the root to enlarge in a distinctive rose shape. These roots became known as wood roses and were highly collectable for a time – a practice that is illegal on Department of Conservation land. Taylor’s Maori travelling companions told him that it would only grow in the forest. Research has narrowed that down to forest margins and recently disturbed ground, reflected in the 30 or so early succession species that act as hosts, including five finger, lemonwood, mahoe, lancewood, hohuhu, wineberry, pate, putaputaweta
A female flower on the left and a male on the right. Photo: A Holzapfel, DOC. and karamu. Each plant can live for many decades, but once the host dies, so does the parasite. Currently, there are no known cases of its being hosted by podocarps or exotics, but they will grow in pine forests with a suitable host plant understory.
Once widespread, dactylanthus’s range is now only 4 per cent of what it was before humans arrived. Scattered populations remain from Northland to Wairarapa.
Some of the highest densities are in the Waikato. Some estimate that only a few thousand plants are left. The recovery strategy includes covering plants with cages that exclude possums, deer, pigs, goats and stock, but allow bats entry.
Flowering occurs predominantly in autumn, a period when there are few other nectar sources available, and at a time when bats are fattening up for winter. Plants on Pirongia, the Herangi Range and the Hauhungaroa Range flower in mid to late January, much earlier than other known Waikato sites.
On the Coromandel, dactylanthus was rediscovered in 2004 after no sightings for 100 years, but one of the key host trees and its associated parasites died in 2011. Two other Coromandel clumps have already produced inflorescences this season and are expected to be opening around now.
In the Pikiariki Ecological Area next to the Pureora Village, flowering usually peaks around the first two weeks of March. This year, some plants were blooming in early February, which is extremely early. Taylor found dactylanthus just south of Raetihi in March. Flowering has been known in some areas as late as May.
Several research theses have been completed on dactylanthus, but the more we know, the more questions arise about this intriguing and elusive plant. Taylor was right: dactylanthus is remarkable.
Thanks to DOC staff for their assistance with this column.
Want to get in touch with Kathryn, either to suggest a topic or just tell her what you think? Email her c/deborah.sloan@waikatotimes.co.nz.