Mistletoe and its interesting side


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Beyond the Kiss, Mistletoe Helps Feed Forests, Study Suggests

For years, mistletoe has suffered from a split reputation: either the decorative prelude to a sweet Christmas kiss or the tree-killing parasite that must be mercilessly excised for the good of the forests.

Now a recent Australian study has come up with a surprising new understanding of the evergreen plant: It is a key to keeping forest life healthy. Not only should it not be cut out of the forests it affects, but it could also be introduced in injured woodlands to restore them to health.

The mistletoe makeover stems from an experiment started in 2004 in a small woods surrounded by farmland in the upper Billabong Creek area of Australia’s New South Wales. David Watson, an ecologist at Charles Sturt University in Albury, New South Wales, reasoned that the only way to discern the role of mistletoe was to remove it from 17 woodlands and compare them with 11 woodlands where the mistletoe remained and 12 woodlands naturally devoid of the plant.

It was a herculean task to eradicate the parasitic mistletoe, involving cherry-pickers, loppers, a dozen people and two seasons of work, made all the tougher because the Australian mistletoe mimics the trees it takes root on. Moreover, while mistletoe, with its 1,400 species in five families, lives on every continent except Antarctica, it is sparse within each forest. Dr. Watson said he found only a few plants in every acre in the woodlands he worked on.

In all, his team members removed more than 40 tons of the plant, leaving it on the ground for livestock to consume. Then they waited for three years.

Dr. Watson, known in academic circles as “the mistletoe guy,” had long suspected that his favorite plant was a keystone species, meaning it punches above its weight, ecologically speaking, but even he was unprepared for the results. He had supposed that creatures that fed or nested on mistletoe would be affected by its removal. Instead, he found that the whole woodland community in the mistletoe-free forests declined.

Three years after the mistletoe vanished, so had more than a third of the bird species, including those that fed on insects. Bird diversity is considered an indicator of overall diversity. Where mistletoe remained, bird species increased slightly. It was a similar story for some mammals and reptiles, but, in another surprise, particularly for those that fed on insects on the forest floor.

“It’s a bit of a head-scratcher,” said Dr. Watson.

Analysis showed that species of mistletoe play an important role in moving nutrients around the forest food web. That has to do with their status as parasites.

Nonparasitic plants suck nutrients out of their own leaves before they let them fall, sending dry containers to the ground. But because the vampiric mistletoe draws water and nutrients from the tree stem or branch it attaches to, it is more nonchalant about leaving that nutrition in falling leaves. That means the fallen leaves still contain nutrients that feed creatures on the forest floor.

Not only that, but mistletoes make and drop leaves three or four times as rapidly as the trees they live off of, said Dr. Watson. As evergreens, they also do it throughout the year, even when trees are dormant. It is like a round-the-calendar mistletoe banquet.

While no similar mistletoe excision experiments have been performed in North America, where fossil pollen grains suggest the plants have lived for millions of years, scientists in the United States say they, too, have noticed its positive effect on forest life.

David Shaw, a forest health specialist at Oregon State University in Corvallis, pointed to the van-sized “witches’ brooms” formations in old-growth Douglas fir trees in the northwest United States produced by dwarf mistletoe parasites. At onetime, foresters would have pruned those away. Today, they are trying to protect the brooms because they are important nesting sites for the endangered northern spotted owl.

Dr. Watson said it was possible that introducing mistletoe into a damaged forest could help restore it to health.

But introducing mistletoe onto trees could prove controversial. While the parasites are like Robin Hood, stealing from rich trees to feed the forest poor, they can spoil individual trees for lumber. That is especially true of the deforming dwarf mistletoe. Mistletoe is still widely known as the “thief of trees.”

“We’re still in transition in the U.S. from looking at mistletoe as a big pest, a big parasite and damaging to trees,” said Robert Mathiasen, who teaches forest ecosystem health at Northern Arizona University in Flagstaff.

Still, Dr. Watson’s findings add a touch of science to the folkloric view of mistletoe as a tantalizer, inducing people to wait under it for a kiss at Christmas. The custom stems from the ancient Druids, who believed mistletoe could work magic because it grew high in bare oak trees in midwinter where nothing else did, seemingly out of thin air. They cut it down with golden sickles, never letting it touch the ground, and hung it in homes to foster fertility.

The Australian study suggests that the plant does seem to work ecological magic of a sort.



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There is a bunch of sand dune desert that has a thin layer of moss and jack pine covering it in this area. Every pine is one big witches broom because of dwarf mistletoe. These stands are extremly susecptable to fire and with the sand drain well. We 've been fighting the fires to protect the buildings so we've created an unnatural situation.

Good info, the only tree protection reasoning until that new research had been that they've lived together for millions of years so it must be ok. Hopefully more is done with the subject. Any excuse, misletoe, the pine beetles are coming, fire break, development, the humans will get those pines long before the mistletoe does.


I don't quite follow the way in which this article is insulting to anyone?

Challenge preconceived notions and you are always rebuffed by emotional rhetoric. Let us perhaps be contented by the idea that the thousand and even million year relationships between plant species may reveal to us unanticipated insight. These insights may even change the way in which we understand ourselves, so long as well allow that these insights may change the way in which we view the environments around us...in short we have to be open minded.

On an individual basis, mistletoe is a stressor which can lead to tree death, but as we know, the forest is more than just the tree. We as arborists tend to deal with fragmented organisms, like a zookeeper in Edmonton works with African animals whose ability to range has been reduced from hundreds of thousands of kilometers to perhaps hundreds of meters. The trees we work with are fragments of the interconnected ecosystems we remove them from, and we truly are ill informed about the complexity of these ecosystems. Especially when our primary interest to the forest ecosystem tends to center on merchantible board feet.


Active Member
Our native mistletoe affects two two local conifers on the coast. Bishop pine and White fir. Not bad for the most part.

But the English mistletoe has wreaked havoc on a few of our oak species on the inland side. Outright killing whole hillsides of trees. This is not natural, and in this case, it needs to be eradicated.

Lots of different issues with just one little plant.


Well-Known Member
Thanks for posting this. Exactly the kind of thing worth reading! Interconnections between trees and the other life forms they are associated with never ceases to amaze.


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Very interesting Bob, thanks for the info. Good to know. Any chance mistletoe can use a human as a host? I nicked myself with a handsaw while pruning mistletoe and I think it's growing under my skin.