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I was at a party the other day and suddenly a friend ran up to me hollering, 'HEY', then he kissed me! It took me by surprise, that's for sure. Good thing he was a friend.

So it turns out, as I'm sure you've already guessed, this was a holiday party, and I was standing under a sprig of mistletoe. Some romantic soul had hung it from the ceiling. I didn't know that people still followed that tradition, or maybe it's just that I never stood under mistletoe before. At any rate, it got me thinking about mistletoe in general.

There are many different kinds of mistletoe, and they come from all over the globe. Europe, Australia, North and South America, they all have their own varieties. Although, botanically, the plants are very diverse, they all have one thing in common. They're parasitic, or at least partly so. Many, but not all, have green leaves and produce flowers and fruits - those white berries that you see on the stuff you buy. What none of them produce are roots to obtain water and soil nutrients. They grow, up in the crowns of trees, and depend on host plants for their nourishment.

I think that the kissing tradition developed around this plant because it grew up in the air, in the trees, without any obvious means of getting water. There are mistletoe legends from all over Europe. The druids of ancient Ireland and England thought it was sacred, and they used it as a medicinal plant. I just read that among the Anglo Saxons, if two enemies met under the mistletoe, they had to lay down their arms and declare a one-day truce. Isn't that an idea worth resurrecting? Apparently Scandinavians had a similar tradition, and they also had a myth where the goddess of love would kiss anyone who walked under the mistletoe.

In other parts of Europe, the plant was a fertility symbol. It was important to some group's marriage rites. Mistletoe was associated with the old pagan feast of Saturnalia, that's the one that celebrated the winter solstice in mid-December.

So, it would make sense - having enemies make up, being a symbol of fertility, being involved with marriage, and that December connection - of course it would all come together and we'd be kissing under the mistletoe at holiday parties.

The host plant, on the other hand, will suffer to some degree if it's infected with a parasite, including a parasitic plant. Since mistletoe doesn't produce roots, it needs to take whatever's available from the tree where it's growing. The tree pulls water and nutrition from the soil, and the mistletoe taps into that system, which is the only way it's able to survive.

Now, what I am about to say is blasphemy.

When I first moved to Southern Nevada, I was kind of excited when I learned that there was so much mistletoe around. I thought it would be kind of cool to have all that kissing going on. I was wrong. Not about the kissing (I think that would be fine), but about the mistletoe. You can't just go out to the Spring Mountains and cut a tree branch for mistletoe to hang in a doorway at Christmas. Of course, you can't just go cutting up public trees anyway, but the kissing kind of mistletoe is not from around here, and doesn't live here.

What we have here is something called dwarf mistletoe. It doesn't have attractive waxy leaves like the stuff that gets hung up in doorways. It doesn't have those little white berries that are supposed to be plucked with every kiss.

The true mistletoe, the kissing kind, will damage a hardwood, like oak.

Dwarf mistletoe is a different story entirely. This is a group of plants that live on conifers - the softwood trees such as pines, firs, and spruce. You can see the effect pretty easily, as a phenomenon called 'Witches broom'. When you look at a conifer and see an area where the twigs and leaves are densely bunched up, and often brown, you are most likely looking at a dwarf mistletoe infection. It seems to be endemic to the southwest, and current wisdom is leaning in the direction that it can be managed, but probably not controlled, and certainly not get rid of it entirely. An infected tree will not grow in a healthy upright fashion, but in a home landscape this is probably not too much of an issue. Since it spreads from tree to tree, you'd need a good-sized stand for infection, and birds in the southwest don't generally appear to eat the seeds. Lately, biologists have noticed recently that some wildlife actually relies on the witches broom for shelter.

And, if you want to kiss under dwarf mistletoe why not start a new tradition?

For KNPR's Desert Bloom, this is Dr. Angela O'Callaghan of the University of Nevada Cooperative Extension.