Which flowering plant has no green leaves and no roots, looks like a taro with Warts, has flowers with no petals, and smells something like a fermented corn cob?
The answer is Dactylanthus taylorii, variously known as “Daccy”, “flower of Hades”, “fingers of the gods” or “wood rose”.
This unusual plant grows only in New Zealand, and only in the North Island. It is a parasite, living on the roots of forest shrubs and trees such as Pittosporum, Schefflera and Pseudopanax. It doesn’t have a photosynthetic cell in its body, and derives all its nutrients from the host root, which it radically deforms until it looks like a cluster of carved wooden petals.
The genus Dactylanthus, of which taylorii is the only species, is a member of a family of root parasites found mainly in the tropics. That quirk of geological history which bequeathed to these shores the tuatara, kakapo and other unique creatures also gave us the sole southern representative of the Balanophoraceae: the wood rose.
To be accurate, the name “wood rose” should only be applied to the deformed root of the host plant there is nothing woody about Dactylanthus itself. The main part of the plant is a swollen underground stem or rhizome (bamboo and kikuyu grass also have rhizomes). Though subterranean, the rhizome is never so far below the surface that its asparagus-like flowering shoots cannot push up through the forest litter and humus.
It is only during the short flowering season, from February to early April, that the presence of the plant is really noticeable. During these months a profusion of pinky-brown flowers, each one a few centimetres in diameter, studs the forest floor above each plant. The rest of the year Dactylanthus is invisible — unless the soil above it has been eroded, in which case the hard, warty top of the rhizome may be seen.
Even the term “flower” is not strictly correct. Dactylanthus flowers are inflorescences made up of between 10 and 40 fleshy stalks called spadices, each one bearing around 50 highly simplified flowers. In the male, the flower is little more than a single pollen-bearing stamen;in the female, it is more or less just a pistil. Daisy and dandelion flowers are also examples of inflorescences: dozens of “mini-flowers” making up the bloom we see.
Flowering, though brief, is prolific. Each plant may produce up to 60 inflorescences per season, giving a total of 120,000 flowers. However. despite such an enormous reproductive capacity. Dactylanthus seems to have barely held its own in the plant world, and is now in serious decline.Once found from Hokianga in the north to almost as far south as Wellington, the plants are now mainly confined to areas inland from East Cape, through the Central Plateau and south to Wanganui. The species is officially listed as vulnerable, which is to say that it is “under threat from serious adverse factors throughout its range.”
In the past, the main “adverse factor” has been two-legged in form: “Daccy hunters” who dug up the plants, roots and all, boiled off the rhizome and then sold the resulting wood rose (usually mounted and varnished) to souvenir shops.
One “hunter” used the ingenious method of placing his rhizomes in wire baskets which he then suspended in a geothermal pool at Wairakei. A few days later he would return to collect the stripped wood roses. The going price from Auckland gift shops was a dollar a flower.
Lately, however, the finger is being pointed at the possum as the main agent of destruction. The succulent Dactylanthus shoots poking up through the leaf litter must represent an irresistible snack for a hungry possum, and the flowers’ powerful perfume would attract the voracious marsupials from a considerable distance.
One person who is keen to prove a link between the increase in possum numbers and the decrease in Dactylanthus is Chris Ecroyd, the herbarium curator at the Forest Research Institute in Rotorua. For the last three years he has been visiting wood rose sites in the Mamaku Plateau, to the west of Rotorua, and in Pureora Forest, near Taupo, to study the impact of possums and rats on the plants.
Chris Ecroyd began to suspect possum damage after numerous unsuccessful attempts to find flowering Dactylanthus in the Mamaku Forest. He had no difficulty locating rhizomes, but the only flower stems he could find were either dead or damaged. To test the theory that animals were to blame, Chris set up a series of exclosure plots — wire netting cages placed over Dactylanthus rhizomes to keep out rats and possums. Within a week, the rhizomes inside the plots were covered with flowers — up to 30 or 40 each — while unprotected plants remained bare. Further experiments, in which the mesh size of the netting was varied (to allow the entrance of rats in some, but not others) have led Chris to conclude that possums are the main culprits in the demise of the wood rose.
Dactylanthus Taylorii was named after its discoverer. Rev Richard Taylor, a missiunaly, explorer and naturalist who stumbled on the plant during a trek from Taupo to Wanganui in 1845. Thanks to his thoroughness as a diary-writer, we have an account of the exact moment of discovery:
“March 18, 1845 — It was a rainy night, and very cold, wet and cheerless. In walking through the dense, humid forest I was soon as wet as if I had been in the water… I found the Parei myself today. It is certainly one of the most remarkable vegetable productions I have seen, and appears to be the union of fungus with the plant. I passed several, taking them for toadstools, but one more remarkable than the rest caused me to stop and gather it. I then found that it was a plant in full flower, although very much resembling a fungus. It has no leaves, and has a calyx containing a kind of pollen with rather a disagreeable smell. The Natives say it is more prolific than the potato, but will only grow in the forest.”
The name “Parei” is a mystery. The usual Maori names for the plant are “pua o te reinga”, or its shortened version “pua reinga”, and “waewae te atua”. In Maoridom, things that live underground have strong associations with the spirit world. The term waewae te atua, meaning fingers (or toes) of the gods, relates to the subterranean habit of the plant on the one hand, and its fingerlike flowering stems on the other. The English name “flower of Hades” is a distorted translation of pua o te reinga. “Reinga” has associations with the spirit world, in that the spirits of the departed are said to leap from a sacred tree at Cape Reinga (at the northern tip of the North Island) before commencing their journey back to their mystical homeland, Hawaiki, but the concept of Hades is foreign to Maori spirituality.
While Taylor was quite right in his observation that the plant was not a fungus (a common misconception even today), he was incorrect in attributing the smell to the pollen. Dactylanthus flowers contain a relatively large amount of sweet-tasting nectar — up to one and a half millilitres in some specimens — and it is this which gives the flowers their characteristic bouquet. Early botanists described the fragrance as resembling ripe rock melons or daphne. though Taylor appears to have found the smell uninspiring — perhaps the flower was rotting. The smell is certainly unlike that of any other plant in the New Zealand bush.
The possession of strong-smelling nectar is usually an indication that a flower is pollinated by insects, and this is so for Dactylanthus. Ants, beetles, small flies and, in more recent times, wasps have all been observed entering the flowers to sip the nectar. If all goes well (from the plant’s point of view) such visitors will re-emerge from the male flower with a liberal dusting of mealy white pollen. which they will then transfer to the female flowers. Successful pollination results in the production of tiny pepino-shaped seeds about the size of a radish seed.
Seeds may remain on the female spadices for over a year before falling to the ground: germination occurs in spring. The chances of the germinating seed finding a root on which to bind must be very slim indeed. Unless there is a root of the correct type and thickness within about two millimetres of the seed, its meagre food resources will be exhausted and the seedling will die.
The processes by which a germinating seed selects and attacks a root are unknown (presumably a chemical stimulus is involved), but it is clear that the seed is very choosy.One tree may have a large number of Dactylanthus plants of various sizes living on its roots, while a nearby tree of the same species will have none. No one has yet been able to germinate and grow a seed artificially, and until this is done it is unlikely that the secrets of the Dactylanthus seed will be unravelled.
If the probing radicle of a germinated seed does find a suitable rootlet, it somehow penetrates it and begins to take nutrients from the xylem and phloem of the host. Gradually it builds up its rhizome around the root and diverts all nutrients to itself, causing the part of the root beyond the rhizome to die. Inside the rhizome the tissues are moist and spongy, and at the junction between root and parasite the tissues of each plant dovetail in a complex array of cells and structures that are still not understood. Whatever chemistry may be involved, it is here at the interface that the transformation from root to wood rose takes place: a work of natural artistry that is as remarkable as it is varied.