"And this is a salt cedar," she crooned proudly as we approached the fully grown tree. Her fingers moving tenderly through its needles, she described the lovely purple bloom it displayed in spring. She also remarked on how well it had become a part of the garden, filling up that corner nicely and complementing the columbine and lupine just perfectly. I resisted the urge to reply, bit my lip and patiently hung on through the rest of the real estate tour. Eventually, we put the house under contract and patiently waited the 30 days prior to closing.

One of the first things I did after moving in was mix up some two-stroke oil and gas, fire up the chainsaw and rip into the salt cedar's trunk. The whirring blade bit into the same branches that had been caressed a month prior. I took the tree down in three separate pieces, delighting in the cuts, and on my final pass, I shaved the stump close to the ground trying to erase any mark of the tree's existence. Then I bucked the beauty up and put it on the top of the burn pile.

Purple blooms and complementary colors aside, that salt cedar is known by another name outside the realm of the nursery. And I had no plans on having a tamarisk, the scourge of the West, growing happily in my front yard.

Cutting down a tree is serious business in this day of hungry paper mills and salvage logging. It's particularly difficult to drop a tree that was deliberately planted, cared for and nursed into adolescence. However, having a tamarisk in the front yard would be akin to keeping a hyena as a pet. The tree is completely alien to the west and America, having been deliberately introduced as a landscape ornamental. It also has no natural predators and has spread unchecked for the last 50 years, squeezing out natives, sucking rivers dry and destroying habitat. It is little more than a giant weed and is sadly not even the most significant threat to the natural landscape of La Plata County.

In an earlier Durango house, I fell in love with the seemingly mature trees in the back yard. The following spring, the trees were the first to leaf out and then by surprise, they starting dropping thousands of seed pods in the yard. The little medallions formed windrows in our flower beds and even got into trays of vegetable starts. Weeks later, hundreds of shoots started poking their heads up everywhere. Our old-timer neighbor passed by one day and chuckled as he saw us weeding beneath the 80-foot-tall trees. "I see you've met your Siberian elms," he said. "Man, those things are a pain in the ass. And you know what? I bet those trees have only been there for 15 years." I found myself mixing oil and gas.

Last weekend, as we floated into the relatively pristine, wilderness stretch of the Lower San Juan River in Southeast Utah, there were no Siberian elms. However, tamarisk was everywhere. It blotted out river banks, covered one-time beaches and draped over the river, threatening to close narrow stretches altogether. A vast number of Russian olives, another ornamental tree gone bad, intermingled with the tamarisk.

I was surprised when a member of our party and a Durango resident said, "Boy it's nice to see all these olives against the red rock. It really reminds me of my upbringing."

Another chimed in, saying, "It's just a shame we weren't here a little earlier for the bloom. The smell is just intoxicating."

Once again, where my eyes saw blight, others were overwhelmed by beauty. But the canyon told its own tale. These thorny ornamentals hindered progress on side hikes. They surrounded stands of ancient, gnarled cottonwoods and were choking them out. Hundreds of miles from the nearest landscaping, Russian olives were growing everywhere, flourishing in sand and cracks in the rock.

Knowing that the tree was beginning to get a foothold on the banks of the Animas River, the view was an especially upsetting one. My thoughts turned to a federal push to eradicate tamarisk and efforts in Durango to get a handle on Russian olive.

But then someone commented, "It seems like the kind of tree you could enjoy in your yard as long as you kept an eye on it." The comment neglected the real reason the trees were spreading in Durango, in Farmington and Cortez, in the canyons of the Lower San Juan and throughout the Colorado River Basin someone bought a tamarisk, a Siberian elm or a Russian olive at a nursery, planted and tried to keep an eye on it.

The spread of these new neighbors began in private yards. Maybe we should start getting a handle on them there as well. Once you know what you're dealing with, mixing up a little gas and firing up the chainsaw can be a pretty gratifying experience.