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TREES, PLEASE: Space Invaders: Keep an Eye Out for Tree Tobacco

Tree tobacco's clusters of greenish-yellow flowers. Image courtesy of Miwasatoshi.

By Tim Clancy.

Not all trees are created equal, and not all trees are benign. All over the country, there are trees that are classified as invasive species. California's Invasive Plant Council addresses the problems associated with these species, and its a good resource for information pertaining to plants considered by consensus to be invasive. They are assigned various categories relative to their invasiveness, with some being more invasive than others and some that are problems in one part of the state may not be a problem in other parts of the state.

In downtown Encinitas, there is a botanical jewel just east of the Moonlight Beach parking lot. Back in the 1980s, this area was slated for development. Some local citizens thought it should be preserved for posterity, though, and since the early 1990s, a group of dedicated volunteers from the Cottonwood Creek Conservancy has worked a couple times a month to aid in cleanup and restoration. Their hard work paid off and now children of all ages can enjoy plants and trees native to the area.

Besides natives, there are some unwanted residents. The most persistent of these is Nicotiana glauca, commonly known as tree tobacco. I first noticed this species of wild tobacco some fifteen years ago. It was growing in the middle of Highway 101 across from The Kraken in Cardiff, but I wasn't familiar with the plant. After describing it to a colleague, he told me it was tree tobacco, native to South America.

Introduced in California in the early 1800s as a landscape plant, tree tobacco now calls the southwest home. The plant favors disturbed areas and can be found in all sorts of locations; it's drought tolerant and can tough out all sorts of conditions. It is described as a tree or shrub that grows up to twenty feet tall (see photo on left) and has branched clusters of greenish-yellow flowers. It is a fast grower and can produce 10,000 to 1,000,000 seeds a year. It's also toxic to both animals and humans; all in all, it's kind of a mean plant.

Since the first time I noticed it, I've observed tree tobacco more and more frequently over the years. Not unlike when you buy a new car... all of a sudden, you see that car everywhere. I have seen it in almost every city in San Diego County, as well as in other cities outside the county. In Norco, I saw a field of tree tobacco that reminded me of a farmer's field of corn—it was that thick and there were at least three acres of it.

The frequency of tree tobacco sightings has demonstrated to me just how insidious an invasive species can be. It is a real problem at Cottonwood Creek in Encinitas and many volunteer hours have been allocated to its control. Hours that could have been used elsewhere. Next time you're out driving, keep an eye out for tree tobacco. I am sure you will be amazed at its prevalence. Oh! And check out Cottonwood Creek Conservancy's Moonlight Beach restoration project.

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