Mistletoe grows on the branch of an oak tree in Briones Regional Park. Photo: kqedquest.

Have you been hanging out under the mistletoe at holiday parties, hoping for a kiss? Well, that mistletoe is more than a Christmas kissing custom. It’s a parasite that can harm trees—and a potential treatment for cancer.

Mistletoe lives on the branches of trees, and is a hemi-parasite; it produces some of its own food (it has green, photosynthetic leaves), but it gets nutrients and water from its host plant (its roots tap into the host plant, rather than the soil). If the mistletoe grows big enough, they can do some damage. Large mistletoe plants can weigh down tree branches and make them more likely to break off during a storm. If there are many mistletoe plants in a single tree, they can stunt the tree’s growth, make it more susceptible to disease, and even kill it.

There are several species of mistletoe living in California. Pacific mistletoe, Phoradendron villosum, lives in the western US, and is a parasite on oak trees. European mistletoe, Viscum album, parasitizes a wide range of species, including apple trees and maples.

Mistletoe is spread from tree to tree by birds. They eat the white berries and spread the sticky seeds with their beaks or in their excrement.

Despite its parasitic tendencies, mistletoe has long been thought to have healing powers. In Greek legends and druid folklore, mistletoe was used to treat disease. And since the 1920s, scientists have been investigating mistletoe extract as potential cancer drug.

Several laboratory studies have shown that mistletoe extract can kill cancer cells—though other studies have shown that the extract has no effect. It seems that mistletoe growing on different types of trees (like apple, pine, oak, or elm) may have different medicinal properties.

Mistletoe extract seems to boost the immune system, by increasing the production and activity of white blood cells. (Don’t try this at home—mistletoe can be poisonous.) Several clinical trials, mostly in Europe, have tested mistletoe extract as a form of adjuvant therapy—a treatment that is given to cancer patients after their primary treatment, to decrease the risk that cancer will return. Patients were treated with mistletoe extract (injected under the skin), along with radiation and chemotherapy. Patience who received the mistletoe extract fared better than their counterparts who did not receive it. Additional studies are underway: check out the National Cancer Institute’s Questions and Answers About Mistletoe.

While you’re standing awkwardly under the mistletoe at your next cocktail party, you can wait quietly for that special someone, or you can strike up a conversation about mistletoe’s medicinal properties.

Related posts:
Briones Regional Park Exploration

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The guts of the system are hidden underground.

They LOVE announcing like, squawking little birds, exactly what it is I'm doing in there. They knock each other over for the chance to flush the toilet. But it seems the best part of all is giving it a hero’s send-off: "Bye-Bye, Poo-Poo! Bye-Bye, Poo-Poo! Bye-Bye, Poo-Poo!" Apart from it just being sort of fun to say, I don’t think that I’m imagining that they are experiencing a kind of satisfaction in making it go away. Call me jaded but I think my own enthusiasm for the process has faded somewhat since I was their age. But after producing Wastewater Woes: Sewage Spills in SF Bay, I've learned some things about sewage collection and wastewater treatment systems that are good to be aware of.

When one of the 47 wastewater treatment plants around the bay has a spill or an overflow during wet weather, it's unlikely that Bay Area residents consider that it was caused by anything that we've done or neglected to do. But I learned that one of the main reasons for so many sewage spills in San Francisco Bay- both from the treatment plants and the collection systems underground- is that those of us who use and depend on the sewage system don't really understand it. Water and sewage customers need to be conscious of a few key facts:

• The water that's flushed down the toilet, used to wash clothes or dishes, or runs while we brush our teeth ultimately ends up getting treated then is discharged into the bay or the ocean.

• Putting grease down the drain, flushing rags, feminine hygiene products or anything but toilet paper down the toilet can lead to blocked sewage pipes and dangerous spills in the collection systems.

• Years of neglecting our cracked and crumbling sewage collection systems, including privately-owned sewage lateral pipes that connect every single home and business to the city-owned sewage mains, has resulted in the inflow of great volumes of rainwater to the collection system as well as spills and overflows downstream at treatment plants.

Sure, sewage is not the most pleasant thing to contemplate and it's understandable that most people don’t give it a second thought because the guts of the system are hidden underground. But it is precisely this "out of sight, out of mind" mentality that has led to untreated sewage spills in San Francisco Bay becoming a significant source of pollution that can have harmful impacts on people, animals and habitat. The cost of fixing the Bay Area's systems is estimated at several billion dollars. Obviously, that won't happen overnight. So in the meantime, have your own lateral inspected and repaired and don’t be surprised if your sewage rates continue to creep up.

For my own part, I will strive to teach my boys responsible flushing and instill in them a little bit of curiosity about what exactly happens AFTER we flush the toilet.

Watch the Wasterter Woes: Sewage Spills in SF Bay television story online.

UPDATE: Also see our Interactive Map of Bay Area publicly-owned sewage treatment plants and spills.

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